In The Maze Runner by James Dashner the plot (so far) is that Thomas is trapped in the Maze. The Maze is a place that Thomas has been sent to for reasons unknown. He wants to become a runner and explore the Maze and hopefully find a way to escape. There are other kids there they are known as gladers (they live in the Glade in relative safety). These other gladers have effected the charicter of Thomas in quite a few ways along with some of the events that have happened since his arrival.
Since Thomas' arrival there have been a few firsts. The first girl to enter the glade came up in the box a day after Thomas' arrival. There was also a "dead" Griever (kind of like robotic zombies). This gets Thomas a lot of attention. He becomes a slightly notorious figure around the glade. People are constantly asking him questions along the lines of 'do you know that girl?'. Gladers seem to think that these strange events are due to Thomas' arrival and he has some sort of connections with these events. This has made Thomas become a slightly irritable person. He INSISTS he does not know the girl who came up a day after he did. The Box also said "she is the last one" on it. It is implied that this means that she is the last glader that will be sent up ever. This puts more attention on Thomas because they think that in his past life that he does not remember.
Alby and Minho along with other runners affect the character of Thomas a lot. Alby and Minho are runners and they seem to feed Thomas' strange desire to become a runner. I think that its because Thomas' finds all the other jobs to be quite boring. Who wants to toil long and hard to garden crops when you could be out in the Maze fighting for your life against robo-zombies? He is allways thinking if not saying that he wants to be a runner. He sees all of the hard work that Minho and Alby put into their work in order to go out and draw maps of the Maze. Risking their lives for the greater group. I think that Thomas' is sort of an adrenaline junky of sorts who wants to do something useful and exciting while he is staying in the Maze.
In conclusion Thomas is influenced by the people around him along with the events that also take place. He has become a little bit of an insistent character because of his constant questioning because of his supposed connection to the girl sent up in the box. He is also effected by the runners because it feeds his desire to become a runner. Then again, now that he's trapped himself in the maze, he will definately get an unwanted taste of what life outside the Glade is like. Good luck.