Jackson "Jack" Darby is a 16 year old teenager who has wanted a motorcycle since he was little.
Jack's father had left him and his mother for unknown reasons. Jack worked at KO drive burger joint where he was often harassed by bullies. He wished to save his money in order to afford a motorcycle in order for him.
Meeting the Autobots
Until he met the Autobots, Jack was living a normal life in Jasper, Nevada where he worked at a "K.O Burger,"a local burger joint. Jack got picked on by bullies such as "Vince" because of his job and wishes for something more. After he gets off from work, Jack sees a beautiful motorcycle, and expresses an interest in owning one of his own someday, not knowing this "motorcycle" is actually an Autobot.
Jack is spotted with the motorcycle by a Vehicon duo, who take him to be an ally of the Autobots. The motorcycle gets Jack to safety before tossing him off in an alley, and telling him he never saw her. Jack runs but the Vehicons split, one after the Autobot, the second after him, forcing Arcee to save him again. As they flee, they are are joined by Bumblebee, and they end up fighting the Vehicons in front of another human kid, Raf. Arcee tells them to run and they deal with the Vehicons. The next day, Jack and Raf meet up, Jack saying they should just forget the whole thing happened, only for Bumblebee to show up and Raf goes with him, telling him Arcee will take him. Jack is reluctant to go anywhere with Arcee, who tells him that his life may depend on it when they're spotted by a teenage girl named Miko Nakadai, forcing them to bring her along. Arcee and Bumblebee bring the three kids to the Autobot secret base in an old missile silo and bunker, where they are introduced to the rest of the team, Bulkhead, Ratchet, and their leader, Optimus Prime. Optimus educates the three humans about the Autobots and their sworn enemies, the Decepticons and the war that ravaged their home planet, Cybertron. The Decepticons minions, the Vehicons saw Jack and Raf associating with Arcee and Bumblebee, leading them to believe that the four of them are allies, which makes the humans by default the Decepticons' enemies. Optimus assigns Arcee to Jack, Bumblebee to Raf, and Bulkhead to Miko to act as the kids' protectors, and have them hide when Special Agent William Fowler arrives, not happy about the 'bots and 'cons' activities. Optimus assures Fowler they can handle the threat and the agent leaves. He sends the children home with their protectors and Jack is caught by his mother with Arcee in her vehicle mode, mistaking her for an ordinary motorcycle. Though initially not happy that Jack "bought" a motorcycle without her permission, he managed to cover up his secret and explains himself reasonably well and gets away with it, only for his mother to make him promise to give her a ride on the motorcycle and always wear a helmet at all times. The next morning, Arcee woke him early, though it was a Saturday, as they had to get to the Autobot base promptly.
On the way back, Arcee showed off some fancy riding skills. They reached the base at the same time as Bulkhead and Bumblebee, however Optimus immediately left on a mission with Ratchet. Arcee, left in charge, opted to go out on patrol with Bumblebee, leaving the kids with Bulkhead as a carer. When Miko suggested they get a band going, Jack offered the use of his harmonica skills, which Miko didn't seem particularly keen on. After having his ears punished by Miko's electric guitar solo, Jack and the others had to hide behind Bulkhead to avoid being seen by Agent Fowler, but Miko's guitar gave them away. Bulkhead managed to prevent Fowler from taking the three kids into custody, but a short time later they detected a distress call from Fowler's helicopter, suggesting the agent had been captured by the Decepticons. After Bulkhead bridged out to try for a rescue, Jack and Raf realized that Miko had surreptitiously followed the Autobot. Figuring that Bulkhead might not have noticed her, the pair reactivated the ground bridge and followed Bulkhead, only to arrive near the Decepticon ship and accidentally alert the sentries stationed on it.
Bulkhead rescued the pair while they were under fire and dropped them off behind some cover before heading into the ship. Unfortunately the pair were spotted by the Decepticons a short time later, and found themselves being carried to the brig. Arcee and Bumblebee rescued them both, and they all found Bulkhead and Miko, but the kids soon discovered that the middle of a battle is not the healthiest place to be. The Autobots cleared out a room for them to hide in, and Jack immediately told Miko off for getting them involved. Their arguing upset Raf, and the pair tried to console him, before Jack noticed a computer display appeared to be showing important data. They were interrupted by a Decepticon, which led Jack to have to make a daring save to prevent Raf from being shot. Jack got Miko to take a cameraphone picture of the display before they hastily left the room. Luckily the Autobots were returning from having rescued Fowler, and Bulkhead was able to destroy the Decepticon. After returning to base, Jack decided that he no longer wanted to be with the Autobots if he was going to be in danger constantly and wanted to go back to "having a normal life". Arcee paid him a visit as he arrived at his KO Burger job, and managed to persuade him to return with her to the Autobot base. No sooner had they arrived than the Autobots left on a mission into space to stop the Decepticons from using their space bridge. It became apparent that the Decepticons were targeting the bridge using the Giant Sized Array radio telescope in Texas, and Jack suggested the three kids bridge there so Raf could override the system onsite. They did so, but it turned out that Soundwave was also onsite, and the Decepticon dispatched a tentacle to interfere with their attempts to stop him. Jack and Miko were knocked aside by the tentacle, however Jack was not impressed by Miko's attempts to fight back when the tentacle took the axe she was holding. They followed it to the next room to find Soundwave had locked the dishes on Cybertron. The kids returned to base where they kept track of the other Autobots' work in blowing up the space bridge, however they returned with Arcee in a bad way. After she and Jack shared a moment, she seemed much better by Darkness Rising, Part 5.
Assigned to do a science project for school, Jack opted to get a motorcycle engine working, but was surprised when Arcee turned out to be clueless in the area of automotive engineering. The project was eventually taken over by Ratchet who built something which could be said to resemble an engine. When Jack switched it on at school, it promptly ran riot and it can be assumed he did not achieve a favorable grade.
The kids arrived at base on a Saturday just as Optimus and Arcee were preparing to go on a mission. Jack was initially keen to come along, until he found out they were headed for the Arctic. Instead, he stayed at base and played videogames with Miko. Of course, just as he was winning, the power went out momentarily and stopped the game. The cause of the malfunctions became clear when Raf returned to the control room with a small metal critter the Autobots called a Scraplet. Jack attempted to protect Ratchet as the Autobot worked on the broken ground bridge, and used a fire extinguisher to freeze the Scraplets that attacked them. Once he and the other kids had help the Autobots, a plan was formulated to get rid of the Scraplets, and the three kids repaired an energon fuel line, enabling the Autobots to send the Scraplets to the Arctic. Later, the kids helped with repairs on Bulkhead and Bumblebee.
Jack was surprised to learn there were more Autobots out in space when Wheeljack arrived on the planet. The Autobots celebrated his arrival, though Jack mostly hung out on the sidelines with Arcee. When Wheeljack turned out to be a Decepticon imposter, Jack wondered if there was a real Wheeljack, and was alarmed when the phony took Miko hostage. Following the Imposter's ejection from the base and the arrival of the real Wheeljack, the Autobots had another party and Jack, Raf and Bumblebee busted out some dance moves. The three kids turned out to see Wheeljack off when he returned to space.
When the Autobots helped Fowler move a hi-tech device, the kids observed their progress from base with Ratchet. The Dynamic Nuclear Generation System was in danger of being captured by MECH, so Jack and Miko ground bridged to the speeding train it was on in a last-ditch attempt to defend it. Jack grabbed a fire extinguisher to wave at the incoming MECH goons, but in the end they retreated after seeing Optimus. Silas blew up the track ahead of the train, and for a few moments Jack and Miko thought they were doomed, but Optimus managed to stop the train in time.
When Miko and Bulkhead arrived at base following Miko's detention, Jack loudly asked what she had done this time. When the Autobots later discovered that an Energon Harvester was in an Earth museum, Jack and Raf found themselves volunteered by Miko to go in and retrieve it, despite Jack's protest that what they were doing was theft. They were sent in on a scissor lift via GroundBridge and successfully pinched the device from the statue holding it. During their escape, Miko was caught by a security guard, and Jack and Raf ran into Soundwave, who swiped the Harvester off them. Back at base, Jack wondered how they were going to free Miko, and Ratchet revealed the replica Harvester he was working on to replace the stolen one. Jack resigned himself to the idea of adding forgery to his list of crimes, which now already included theft.
While talking to Sierra one day after school, Jack was challenged to a race by school bully Vince. Though Arcee reminded Jack of the rules, Vince's disparaging of her vehicle mode caused her to reconsider, and Jack took up Vince's challenge. They trounced Vince in the race, though Arcee still wouldn't let Jack offer Sierra a ride and told him to keep the whole thing a secret from the other Autobots. When it turned out that Miko and Raf had already found out, Jack swore them to secrecy too. The next day, Vince challenged Jack to another street race, and with Sierra watching, Jack was compelled to agree. Arcee refused to take part, however Jack instead managed to get Bumblebee to help him. He and Bumblebee joined the street race, but so did Knock Out, and they quickly found themselves under attack by the Decepticon. Jack struggled to understand Bumblebee's beeping. They lost the 'Con, but Vince confronted them, drawing Knock Out's attention, and the bully was captured. When Arcee and Bulkhead arrived, Jack told them what had happened, and accompanied Arcee to the storage lockup where the Decepticon was hiding. He later spun a story to Vince, covering up the whole affair. The following day, Arcee allowed Jack to take Sierra for a ride "just this once".
Jack accompanied Arcee on a safe mission to a remote wooded region to scout an energon deposit. When they found a downed spacecraft, Arcee began acting cagey and dropped him off a fair distance from the ship as she believed it wasn't safe for Jack and didn't explain why. He hiked his way back and eventually found her engaged in combat with newcomer Airachnid. After her foe pinned her to a rock with a glob of webbing, Jack attempted to free her stating "partners don't ditch partners" and mentioning Arcee being afraid which isn't her typical behavior, but fled when Airachnid recovered and began chasing him, intent on adding his head to her "trophies". Though clearly outmatched, Jack made it back to the crashed ship, where he used his pocket knife and fire starter to light a stick, igniting energon leaking from the ship and causing it to explode with Airachnid atop. Unfortunately she survived and globbed him to a tree, but Arcee arrived in time to save him, and Airachnid was forced to flee underground. Jack found that Arcee subsequently had more respect for his ability to face danger.
After Optimus was struck down with a Cybonic plague and Arcee and Bumblebee infiltrated the Decepticon ship, the three kids watched Ratchet monitor the pair's progress as Arcee patched Bumblebee into the comatose Megatron's mind to find the cure. Jack was a spectator for a basketball game between Bulkhead and Bumblebee, and observed that it was starting to turn into a dodge ball match instead. The next morning, he received a phone call in class from Raf, who reported that Bumblebee had failed to pick him up for school.
When Miko seemed totally disinterested in a mission the Autobots were going on, Jack and Raf suspected she was up to something, and sure enough, she made a break for the GroundBridge. Jack tried to stop her, but only succeeded in dislodging her cellphone, and he and Raf were forced to follow her through. Once the Autobots spotted the trio, Ratchet ordered them to return through the bridge, however interference from a Decepticon GroundBridge caused a disruption which deposited the three kids in the Shadowzone. Unable to be seen or heard by the Autobots, they were pursued by Skyquake who had been resurrected as a zombie by Starscream. Arcee attempted to ring Jack, but though his phone rang, they were unable to communicate through the interference. Jack was able to send a text message to Miko's phone back at base. The three kids attempted to use Starscream's severed arm to fend off Skyquake, but only succeeded in dislodging the zombie's arm, which began chasing them. They escaped back to the real world through a portal created by Ratchet. Back at base, and much to Jack's amazement, Miko offered to take responsibility for the whole mess.
Mom Finds Out
Arriving home one night, Jack was met by his mom, who was upset that he was breaking curfew and had been neglecting his job and schoolwork. She grounded him for the next few weeks, banning him from using his motorcycle. What's worse, there was no way Arcee would be able to stay in the garage, though she promised to try and get home before June Darby did each night. The next night Arcee failed to get back in time and had to sneak in after Jack's mom had already seen the empty garage. Jack ended up explaining about the Autobots, but she didn't believe him. Later that night Jack returned home to find a communicator from MECH telling him they had his mother. He and Arcee followed the Silas's instructions, finding the MECH hideout in an abandoned factory, but were shocked to discover that Airachnid was also involved. The 'Con gave Jack six minutes to rescue his mother, however he was able to pickpocket Silas's radio before he began his search. He found June in time, but Airachnid reminded him that the task was to rescue mom, and webbed his hand to the floor. While Arcee and Airachnid fought, Jack freed himself with an iron bar and helped Arcee by pouring concrete on top of the 'Con. Though it was only a temporary win, it gained them enough time for Fowler, alerted by Jack over the radio, to arrive with helicopters and force Airachnid to retreat. Jack and Arcee later look Jack's mother to the Autobot base to meet the others.
Preparing to help Arcee with some routine maintenance, Jack was annoyed when his mom turned up at the base and her questioning about whether it was safe ended up with Arcee instead leaving on a mission with Bulkhead. Jack stayed at the base and listened as they reported back that the Decepticons had used a polarity gauntlet to stick them together. When Miko complained that Arcee was as bad as Jack's mom, June asked if she was really that bad, and Jack refused to answer. After Arcee returned, Jack went to greet her, but June interrupted him so she could give Arcee an apology.
Jack and Miko accompanied Arcee and Bulkhead to an abandoned energon mine. When Miko decided to go inside, Jack persuaded Arcee to let him go in too. While exploring the mine, he and Arcee stumbled on Megatron and Starscream. A firefight ensued, during which there was a cave in and Jack lost track of the others. He found an old Decepticon mining drill and managed to activate it. In the process of digging his way out, he found Megatron, now buried in rock, who suggested Jack take the opportunity to finish him off. Jack declined, believing it was not what Optimus would have wanted, and instead used the drill to rescue Miko from Starscream. The two kids were soon reunited with their Autobot friends and escaped the mine.
Jack helped Raf surf the web looking for conspiracy sites with photos of Autobots on and was surprised when their antics elicited a laugh from Ratchet. When Raf was severely injured during a mission, Jack called in his mom to help, and watched as she and Ratchet worked to save Raf's life.
Chosen by Prime
When his mom decided she was going to take Jack and Miko with her so they wouldn't be endangered by the Autobots, opted to stay much to his mother's dismay, believing that they were all endangered by the Dark Energon. He was pleased when she came back safe and sound after an encounter with a tornado, though she still grounded him. Jack was thus still at the base when the Autobots and gathered humans worked out that Unicron, the greatest evil in Transformer history, was at the center of the Earth and likely waking up.
The humans listened as the Autobots battled giant stone Unicrons and as Megatron arrived to offer to help the Autobots defeat Unicron. When Jack wondered about siphoning Unicron out of the Earth's core somehow, Raf and Ratchet explained that Unicron was the Earth's core and it wouldn't be possible to remove him. The humans hid as Megatron arrived, but after Raf ran out to confront the Decepticon leader, Jack had to restrain him. Megatron recognized Jack from their earlier encounter. Before leaving on the mission to the Earth's core, Optimus presented Jack with the key to the GroundBridge power supply for safe keeping. The humans all watched the Autobots and Megatron step through the GroundBridge into Earth's core.
Ratchet told the kids about Optimus past when he was Orion Pax, and how he got the Matrix. Jack was shocked when Ratchet revealed that the key Optimus had given him was actually the Key to Vector Sigma. The kids all took shelter underneath Ratchet when the ground started shaking, but were overjoyed when it turned out Prime's team had succeeded. They welcomed the Autobots back, but were shocked by the loss of Optimus, who had become amnesiac.
When it was determined that accessing Vector Sigma would be the only way to restore Optimus's memory, Jack was more than willing to go, but they lacked a way to reach Cybertron. He had a brief encounter with Sierra when she came to visit him at his after-school job at KO Burger, though that didn't go so well. Neither did the Autobot's hunt for Optimus, however Jack believed that they would be able to commandeer the Decepticon space bridge when it was completed and reach Cybertron.
Once the Autobots located and secured the space bridge, Jack and Arcee went through, arriving on Cybertron. They soon found the Key to Vector Sigma was pointing them towards Kaon and headed in to the former Decepticon stronghold. While Arcee was kept busy by an Insecticon, Jack headed down to the Victor Sigma chamber and began downloading information into the Key. He was soon trying to fight off a swarm of scraplets, but lucked out when the Insecticon arrived and he was able to divert them to attacking it instead. With the Key fully charged with info, he and Arcee returned to Earth where he transferred it back to Optimus, restoring the Autobot leader's memory.
Jack and Arcee managed to undermine Raf's cheering up of Bumblebee after Bumblebee lost the ability to transform.
He and the other kids hung around for an attempted transplant, and subsequently covered for Bumblebee when he went to get his T-Cog back.
The kids were racing toy cars when Fowler reported being attacked by Optimus. They stuck around as Optimus returned and it turned out he was being impersonated by a MECH creation.
After the Nemesis became sentient, the kids GroundBridged aboard with Fowler to try and download the Iacon database. When they learned the ship was heading for New York City and Fowler was rendered unconscious, they headed for the power core. Miko and Raf ended up playing hide and seek with one of the ship's manipulator arms which Jack tricked into operating the energon flow lever. After succeeding, they high-tailed it back to Fowler and Jack attempted to retrieve the transfer drive only for Knock Out to recover. He was rescued from the Decepticon by Ratchet.
Jack and Miko volunteered to go to Manhattan with Arcee and Bumblebee in search of one of the relics. The two kids encountered Vogel, a sweeper train driver whom they took into their confidence. With his help, they used the sweeper train to hit Knock Out, but this resulted in the train barreling out of control. With a little assistance from Arcee, they stopped the train by running it into Knock Out, and subsequently got Fowler to draft Vogel to ensure his silence.
They returned to base to find Bulkhead had been critically injured on his mission and Ratchet was frantically working to stabilize him.
While helping Raf cover up the Autobot presence on conspiracy websites, Jack spotted a crashing Cybertronian escape pod. When the team returned from investigating it having picked up Smokescreen, Jack gave the new Autobot a tour of the base, including the storeroom where they were keeping the relics. He also took Smokescreen to pick out a vehicle form, however Jasper's lack of options made things somewhat difficult.
Jack was at the Autobot base when Raf called him to report being grounded. He, Miko and Fowler were sent via GroundBridge to Raf's house when the Decepticons got control of a Project Damocles satellite, and assisted him in destroying the satellite.
Assigned to help Smokescreen learn to fit in on Earth, Jack was pulled into playing a series of pranks. The Autobot's bad influence resulted in Jack accompanying him into the field to find an Iacon relic, and when they ran into Megatron, Jack was chased by Insecticons. Though the other Autobots came to his aid in time, Arcee was unhappy with him and sent him home.
Jack was perturbed by the Autobots increasingly leaving the three kids out of the loop. They learned that the Autobots were preparing to return to Cybertron, and later when Jack tried to ring Ratchet to find out why they hadn't been picked up from school, Ratchet merely told him the Autobots were busy. The three kids were kidnapped by Starscream, Soundwave and Knock Out, and taken to Cybertron for use as hostages.
Jack was exchanged by the Decepticons for two of the Omega Keys the Autobots possessed since Megatron noted he had been worth entrusting the Matrix of Leadership with, and he later returned to Earth after Optimus's destruction of the Omega Lock. With the Autobot base under threat from the Decepticons, Arcee and Jack left through the GroundBridge together for elsewhere in the United States.
On the run, Jack figured sending a text message to his mother wouldn't hurt. Unfortunately Jack was wrong and some Decepticons immediately came to attack him. He and Arcee blew up a gas station to get rid of them before speeding off. After a stop at an abandoned farm house, the pair were stopped in the road by a landing spacecraft which turned out to be the friendly (or at least semi-friendly) Ultra Magnus. Joining Magnus on board his ship, Jack was soon reunited with the other two kids and his mother as well as the other surviving Autobots.
As the Autobots set up their new base, Jack narrowly saved Miko from being squished by a lobbing ball. The kids were surprised to learn that the creatures of myth were actually Predacons sent to Earth by the Decepticons. During the Autobot and Decepticon quest for various Predacon fossils, Jack was uncomfortable when Agent Fowler and his mother June went after one without Autobot backup. Their delayed return made him anxious, and he reacted poorly to Raf's suggestions that they might have gone on a date. After discovering that the pair had been kidnapped, he contacted Arcee, who was on mission with Wheeljack and requested their assistance. Much to his relief, his mother and Fowler were safe, though they appeared to have grown rather close. Jack was similarly bothered seeing Arcee and Wheeljack getting along better than usual, but calmed down upon seeing that Arcee had apparently been more interested in helping Wheeljack patch things up with Bulkhead. After Ratchet was kidnapped by the Decepticons, Jack had a conversation with Fowler, in which Fowler surprised him by suggesting that he join Unit E when he was old enough. He was further surprised (unpleasantly) to learn that Fowler got the idea from discussions he'd had with June about Jack.
Jack and his fellow humans played a fundamental role in the defeat of Megatron and the restoration of Cybertron. As the Autobots attack the Nemesis to stop the Decepticons from cyberforming Earth with the restored Omega Lock, Jack comes up with a plan to take the bridge after Ultra Magnus and the Wreckers were delayed by Soundwave. Using a Groundbridge to transport himself and Miko in the Apex Armor onto the bridge, they quickly dispatch the remaining Vehicons and trap Soundwave in the Shadowzone by tricking him into combining his Groundbridge with theirs. With the Nemesis under his control, Jack manages to maneuver the ship away from Earth, thereby stopping the plan to cyberform Earth.
After the restoration of Cybertron and the departure of most of Team Prime, Jack is given the opportunity to become a field agent, (albeit a counseling position until he comes of age). He and Arcee share a tender farewell as she and the other Autobots leave for Cybertron.
Jack is something of a reluctant hero, as he was hesitant to join the Autobot cause. Quite mature for his age, Jack looks out for Miko and Raf like a big brother, and has a sense of responsibility that impresses even Optimus, who saw fit to entrust Jack with the Key to Vector Sigma. According to Ratchet, before Optimus became a Prime, he was a lot like Jack.
Although he doesn't go looking for danger, danger seems to find Jack because of his loyalty to the Autobots, however he is willing to carry out the task at hand, showing a sense of duty, as he did when he and Arcee space-bridged to Cybertron to locate Vector Sigma and recover the Wisdom of the Primes to restore Orion Pax to become Optimus Prime again.
Even so, Jack has his own moments of teenager-based irresponsibility, immaturity, etc.
Jack is a skilled motorcyclist and learned mechanical/technical-engineering from his time with the Autobots. He has proven to be athletic as shown when he evaded Airachnid while he was being hunted down and being able to climb on an immobilized Megatron and Knock Out.
Besides that, Jack has shown to be rather resourceful and quick-thinking, such as using an energon leakage and makeshift torch to destroy Airachnid's ship, directing a swarm of Scraplets towards an Insecticon to stop them from devoring Vector Sigma and using Soundwave's "relocation" trick against him.
After being entrusted with the Key to Vector Sigma, he recieved the power to activate Vector Sigma, an ability only a Prime or one chosen by a Prime could possess.
Jack has a normal loving relationship with his mother although sometimes she can find him acting a little irresponsible, but still loves him greatly after his father left June grew to be overprotective of him often reminding him to call her about his whereabouts.
In Crisscross when Jack returned home after unknowingly breaking curfew she grounded him as well as forbidding him to use his motorcycle and instructed him to use a bicycle, however the next day when Arcee was on a mission June was on route to the house when she discovered that the motorcycle was gone, she lashed out a Jack where the latter hesitantly tried to explain about Arcee and the Autobots, but she did not believe him. When June was captured by MECH Jack went along with Arcee to the rendezvous point where Arachnid and Cylas held her captive which ultimately turned out to be a trap leaving Jack completely vulnerable, he attempted to find his mother near the power plant when he eventually found her. Arachnid trapped him with a web as he attempted to escape until Arcee fought against Arachnid. After the battle he introduced June to Arcee whom she thanked. The day after Jack brought her to the Autobot base to introduce her to the team.
June regularly left work early in order to spend time with him, which often annoyed most of the team mostly Arcee and Miko because of her protectiveness over Jack which led to him missing out on a testing mission with Arcee which annoyed Jack, making an angry glare at his mother. When June learned about her problem she had a discussion with Arcee about Jack where she agreed to loosen her grip on him. Yet, she is still concerned about Jack and would do anything to ensure his safety.
Jack rarely interacts with Agent Fowler.
In Persuasion, Agent Fowler talks to Jack about his future and that he is Prime material. Despite Jack having an awkward moment when Agent Fowler hangs with Jack's mom, Jack follows Agent Fowler and helps him out.
Agent Fowler, somewhat, appears like a mentor and a mature role model to Jack.
Jack and Miko became great friends after the meeting up with the Autobots together with Raf. While Miko almost got Jack and Raf killed by Decepticons, she tried to convince Jack to come back to the team. They would hang out and play video games at the base.
In Convoy, Miko held onto Jack's arm while they were on a speeding train heading towards a broken piece of track. When they share a seemingly last moment, Miko moved in to Jack only to snatch her phone from Jack to talk with Raf. They both were thankful when Optimus saved them.
In Orion Pax, Part 2, while it seemed like Miko was jealous that Jack went to Cybertron she was reminded by Jack that she is important to the team.
In Darkest Hour, Jack and Miko looked at each other before leaving their ways with their Autobot partners. Miko seemed to be quite sadden to leave Jack as she wanted to say something as she left with Bulkhead.
In Prey, Miko reunited with Jack in Ultra Magnus's ship where she happily hugged him around the neck and joked around by punching him in the arm referring to him as "weakling".
In Plus One, Miko refers to Jack as her "bro", meaning that she sees him like a brother figure and friend.
In Deadlock, Miko was in the Apex Armor as she pulled Jack from being sucked into the Shadowzone with Soundwave.
Miko deeply cares about Jack and sticks by his side in any situation.
Jack actually has a crush on Sierra as shown in Speed Metal. Jack talks with Sierra and would hang with her whenever he could. Sierra seems to hint and return those feelings. In Speed Metal, Jack takes Sierra for a drive on his motorcycle.
In Orion Pax, Part 1, Sierra paid Jack a visit at his job at KO Burger. Jack was surprised to see her and she notes that she does not see him around. Jack responds by saying they have chemistry together, which Sierra smiles but he meant they have chemistry class together. She meant she does not see Jack outside of school, like at parties or at the mall. Jack responded that he was busy with work, studying for the SAT's and other stuff. Arcee unknowingly interrupts their conversation which made Sierra convinced when Jack meant by other stuff. Jack tries to convince the voice was his mother and a motorcycle with a female figure on it appears. Sierra notes Jack's mother looks good in leather on his bike before leaving, which left her unconvinced if it was Jack's mother.
After meeting Raf, Miko and the Autobots, Jack made friends with both Miko and Raf. Jack acts more like an older brother figure to Raf and Jack is really protective on Raf when he is in danger, like in One Shall Fall.
Raf is like a younger brother to Jack, since he would often hang out with Jack and have their moments as friends. Raf also appears to look up to Jack the most and they act fairly mature as young adolescents.
Out of all the humans, Optimus sees the most potential in Jack. He believes that Jack is very responsible, which impresses Optimus.
In Convoy, Jack and Miko were thankful Optimus saved them when they were inside a train that was heading towards a broken piece of tracks.
In One Shall Rise, Part 2, Optimus entrusts the Key to Vector Sigma to Jack and Jack promised Optimus that he won't let him down. This shows that Jack respects and would help Optimus in any way he can.
In Orion Pax, Part 3, Orion asked Jack if he was worthy and Jack replied by stating Orion had no idea which Jack restored his memories with the fully downloaded Key to Vector Sigma and Orion reverted back to Optimus Prime.
In Legacy, Optimus partners Jack with Smokescreen in hopes of Smokescreen learning the proper ways of being on Earth. It did not work out when Jack as near to getting killed in battle, which made Optimus and Arcee very upset at Smokescreen for bringing Jack into combat.
However, Optimus still respects and protects Jack along with the other humans on Earth. When Optimus left for Cybertron, he gave a glance at Jack and the other humans before going home.
Optimus is like a father figure and role model to Jack.
Arcee is Jack's guardian. Initially the two were suspicious of each other, but as time went on, the two developed a friendship. Arcee soon came to respect and made Jack her junior partner after the events of Predatory. Jack also vouched for the safety of routine tasks to his mother when she became overprotective. When the two were on the run in Beast Hunters, Arcee reassured him that his mother was fine. At the end of the series, when Jack and Arcee said their farewells, her voice implied that she was holding back her tears.
In Deadlock, when Arcee and Jack gave their last goodbyes to each other, Arcee seemed very sad and Jack was full of sorrow. Though Arcee told him to keep in touch or she might hunt him down (in a playful way), she seemed to be sadden to leave her human partner.
Arcee is like an older sister figure to Jack, even with the exception of Jack's real mother or possibly something more.
At first, Ratchet did not like humans which included Jack. However, when Ratchet began working with the humans, he warmed up to them. Jack rarely interacts with Ratchet.
In One Shall Fall, Ratchet compared Optimus to Jack, which Jack seemed a bit surprised.
In Orion Pax, Part 1, Ratchet explained that Jack was chosen by Optimus to protect the Key Card.
Jack and Ratchet have become close friends after a while.
Bulkhead and Jack do not interact much, but they do seem to have a good friendship.
Jack met Smokescreen in New Recruit. Jack helped Smokescreen find a vehicle mode but they were not impressed by the cars that they saw passing by.
In Legacy, Smokescreen took Jack for a joy ride around Jasper. They bumped into Vince on the road, where he threw a burger at Smokescreen's window before taking off. Smokescreen told Jack that they have to stand up for themselves and they ended up trashing Vince's car with burgers. Later, Smokescreen took Jack on a mission to get the next Iacon relic. It turned out to be the Star Saber. Smokescreen was injured in battle after being shot by a Vehicon and Jack was getting chased by a couple of Insecticons. Luckily, team Prime managed to show up and save both of them. Despite being yelled at by the team for putting Jack's life in danger, Smokescreen learned his lesson and stopped his careless ways.
However, Jack and Smokescreen still talk to each other and they remain good friends.
However, in Rebellion, Jack was trying to sound like a Vehicon, but Ultra Magnus was unconvinced.
Upon learning of Megatron's disgraceful actions to Cybertron, Jack no doubt viewed him as an enemy. The first time Jack encountered Megatron was when he was trapped in an underground cave where he eventually found a drill upon his search for the others. After drilling into a wall, he discovered Megatron trapped in-between the rocks, where the Decepticon leader recommended that the latter kill him with the drill. Jack was hesitant, but once Megatron told him that Optimus would do the same, Jack boldly stated that it was not what Optimus would want and proceeded to find his teammates. Megatron was most likely impressed by Jack's willfulness and his decision to allow him to live.
The two would meet each other when Megatron had offered the Autobots a deal by travelling directly into Unicron's body. Immediately when Megatron entered the base, Jack prevented Raf from facing against the Decepticon leader. Megatron then taunted Jack noting that he had remembered his meeting, with Jack only glaring at him. Because of what the latter had previously done to Raf, Jack mostly likely came to despise him even more.
In Darkest Hour, Megatron stated that because Jack was entrusted with the Matrix of Leadership his freedom was worth two Omega Keys.
Jack hates Starscream like the humans and Autobots do.
In Darkest Hour, Starscream mocked Jack and scratched the container that he was in. Jack hates Starscream and would even risk his own life to stop him.
Jack and Vince have a rivalry in school. Vince is an average bully who picks on Jack the most. Jack hates Vince but he feels that Vince's life shouldn't be at stake.
- Jack Darby is named after Alex Kurtzmen's son Jack and Jeff Kline's daughter Darby.
- Jack has similarities to Sam Witwicky in the three live action Transformer films produced by Michael Bay.
- Jack is one of the most popular human characters in Transformers lore. He is frequently depicted in multiple fanfictions based off him and is frequently present in AUs based off Prime.
Main Article: Jackson Darby Gallery