Jack could have the power of super speed. This would let him quickly move around the battlefield, delivering important messages or distractions. It would also be cool if he could use his speed to create mini - tornadoes to disrupt the Decepticons.
Jack could possess the power of elemental control, like controlling fire or electricity. He could use fire to fend off the Decepticons or electricity to short - circuit their systems. This would make him a formidable opponent and a valuable asset to the Autobots.
One possibility in this fanfiction could be that Jack's powers allow him to communicate telepathically with the Transformers. This would give him an edge in battles as he could quickly convey strategies without the need for words. Maybe his powers also include enhanced physical strength, enabling him to hold his own against smaller Decepticons. It could be a really interesting twist to his character, making him more than just a human ally but a powerful force on his own.
Well, in such a fanfiction, perhaps Jack discovers an ancient relic that bestows upon him the power of a Prime. He then has to learn to control this newfound power while facing off against old enemies of the Autobots. Maybe he teams up with Optimus Prime and the others, using his unique human perspective to come up with strategies that the Autobots hadn't considered before.
One idea could be adventure - based fanfictions where Jack and Arcee go on a special mission together. Another could be about them forming a stronger bond as friends and learning from each other's cultures, Jack from the human world and Arcee from the Autobot world. There might also be fanfictions where they face a common enemy that forces them to rely on each other more than ever.
Perhaps he runs to an abandoned military base. In the Transformers Prime world, there could be old military installations that are no longer in use. Jack might see these as a good place to hide, as they may have some remaining defenses and resources that he could use to protect himself while he figures out his next move.
Well, it could be about Jack initially being scared of the Dinobot due to its large and intimidating form. But as the story progresses, he discovers the Dinobot's noble nature. Maybe they team up to fight some common enemy in the Transformers Prime universe.
One reason could be the allure of power. Unicron is an extremely powerful entity, and Jack might be attracted to that power. Maybe he feels that the Autobots' power is not enough to deal with the threats they face, and he sees Unicron as a potential solution. Another reason could be a sense of rebellion. Jack might be tired of the Autobots' rules and way of doing things, and Unicron represents a break from that.
Maybe he runs away because he's afraid for his family's safety. In fanfiction, it's possible that the Decepticons target Jack's family to get to him or the Autobots. To protect them, he decides to leave and lead the danger away from them. He thinks that by distancing himself, his loved ones will be safe.
The cool factor. Batman has a lot of cool gadgets and a mysterious persona. Jack, as a young character, might be attracted to that. He could see Batman as a role model in terms of being unique and having an edge in the fight against evil, which could translate well into his own experiences with the Autobots in the fanfiction.
The Decepticons would obviously be the main antagonists. Megatron would see Jack as a new threat and would try to eliminate him. Starscream might also be jealous of Jack's new status and try to undermine him in any way he can.
One idea could be that the Autobots immediately launch a rescue mission. They use their advanced tracking systems to find Jack. Maybe Ratchet has some new tech that can detect Jack's unique human energy signature. They face many challenges on the way, like Decepticon traps.