His character would develop a sense of fatalism. If he travels through time and realizes that some events are inevitable no matter what he does, he might become a bit more resigned. However, at the same time, he could also become more determined to fight against the things that he can change. For instance, if he sees that the Maze is always going to be a difficult place, he might focus more on getting the Gladers out rather than trying to change the Maze itself. He'd be constantly weighing what he can and can't change, which would shape his character in complex ways.
A possible plot is that Thomas time - travels to a future version of the Maze world where everything has gone horribly wrong. He then has to bring back knowledge or an item from that future to change the present in the Maze Runner world. For example, he might find a way to defeat the Grievers once and for all in the future and has to figure out how to implement it in his own time. Or perhaps he travels to a time when the Gladers have all split up and are at war with each other, and he has to mend the relationships.
There are many interesting fanfictions about this. In some, the kiss might be a moment of sudden realization of their deep connection, perhaps in the middle of a dangerous situation in the maze. It could be a turning point in their relationship, where they finally admit their feelings for each other.
One possible scenario in such a fanfiction could be that after they escape the maze and find a safe haven, Thomas and Teresa start a new life together. Their baby could symbolize hope for the future in the post - maze world. It might inherit their strong will and intelligence, and grow up to be a key figure in rebuilding their society.
In many fanfictions of 'The Maze Runner' that focus on Thomas and Teresa's kiss, it often represents a significant moment of their relationship. It could be a moment of realization of their deep connection. Some fanfictions might expand on the emotions leading up to the kiss, like the build - up of trust and the unspoken feelings they've had for each other during their struggle in the maze.
A possible plot direction is that the news of the baby spreads throughout the group. Some are excited, seeing it as a sign of new beginnings. But others are skeptical. As Teresa's pregnancy progresses, they face challenges. There could be a shortage of medical supplies. Thomas has to go on dangerous missions to find what they need. Meanwhile, Teresa has to deal with the stress of pregnancy and the group's mixed reactions.
Well, perhaps some of the Gladers accidentally get sent back in time to when the Creators were still planning the Maze. They could then try to sabotage the plans from the inside. They might steal the blueprints of the Maze, or change the types of creatures that are supposed to be put in the Maze. This would completely change the dynamic of the original story and create a whole new set of challenges and adventures for them.
One possible plot could be that they are on the verge of a big discovery about the maze. The stress and the shared sense of impending danger lead to a passionate kiss. After that, they become more determined to solve the maze's mysteries together.
Well, there might be an OC who is a technological genius. In the Maze Runner fanfiction, this character could be using his knowledge to hack into the systems that control the Maze. For example, he might be able to find a way to temporarily disable some of the Grievers or unlock hidden passages. Thomas could then rely on this OC's skills to lead the group to safety.
First, give your OC a unique backstory. Maybe they were an experiment before arriving in the Maze. Then, develop a distinct personality. For example, if they're really stubborn but also very loyal. Also, give them a special ability like being able to communicate with animals in the Maze, which can add a lot to the story.