There are a lot of characters in the first Maze Runner and not all of them survive into Maze Runner 2. Thomas and Teresa both survive into the sequel and the male and female protagonists. Teresa has revealed herself to be under the control of WICKED periodically and so Thomas is wary and mistrustful of her. Also in the sequel are Newt and Minho. Newt has become the leader of the Gladers after the previous leader was killed. Everyone is a bit worse for wear in the sequel and there are some signs of limping that wasn’t there for the first movie.
The former leader Alby is gone, he died in a Griever attack after Thomas used the mysterious syringe on him. The syringe seemed to be making Alby better and help Maze Runner First Lookhim to recall the past but it was no assistance against robotic bedbug looking Grievers. Perhaps most impacting is the loss of young Chuck who died protecting Thomas from Gally. Gally is also killed, stabbed in the chest as he continues to rage against Thomas. Chuck threw himself on the bullet that Gally had intended for Thomas.
Losing Chuck is one of the most heartbreaking scenes in the movie. He was young, innocent and he believed in Thomas at every turn. He seemed to be the only true friend Thomas had and this relationship is not replaced with a new confidant in the second movie. Getting revenge on Gally is a vindication of the loss of Chuck but it really doesn’t make up for it. Chuck’s death is the death of innocence and Thomas is never the same after. Things become darker after his death and the second movie is Group_aa more grown up and desperate place without Chuck.
Aris, the leader of team b who was. Along with Thomas and Teresa involves in the building of the maze and with WICKED returns as well. He is also able to speak to the other two telepathically. In Scorched we are introduced to the second female Glader, Brenda who also can speak to Thomas, Aris and Teresa telepathically. None of these telepathic bonds build trust between the characters. It seems that speaking in dreams and mind to mind is in fact a better way to lie to someone than with your mouth. The old character that have been left behind are more in number than the ones the new ones.