Gally

In The Maze Runner, according to Winston, Gally has been stung by a Griever in the middle of the day near the West door some time before Thomas's arrival. Thus he had regained a few of his memories.

Gally was despised by most of the Gladers due to his arrogant nature. However, he was the Keeper of the Builders, which must have meant that he was reasonably responsible. Two years after the beginning of the Maze Trials, Gally witnessed the arrival of a teenage boy named Thomas, whom Gally immediately became enemies with, having remembered just enough to know that Thomas had worked with WICKED.

After being interrogated with Thomas by Newt, Minho got into an argument with Gally that ended with Gally running off into the Maze and going missing. After being missing for many days, Gally eventually returned to the Glade, scared and dirty, and warned the Gladers that the Maze's Creators were going to kill them and that the Grievers would take one of them every night. Plagued by a nameless terror as the Grievers attacked the Homestead the first night, Gally snatched planks barricading windows and hit Newt with one of them. Thus a Griever managed to penetrate the Homestead and seized Gally, running off into the Maze.

Gally was brought to WICKED and kept there for several days. When the surviving Gladers made it through the Griever Hole, Gally emerged from the shadows along with Ava Paige with a knife, and while under control of WICKED, attempted to kill Thomas by throwing it at him. A young Glader named Chuck jumped in front of the knife and was killed in Thomas's place. Thomas, distraught by Chuck's demise, attacks Gally, punching him repeatedly in the face and severely injuring him. While Gally and Thomas fought, a group of adults enter the chamber and kill the WICKED agents. Thomas knocks Gally unconscious and flees with Teresa and the other Gladers.

In The Death Cure, unknown to Thomas and the other Gladers, Gally was taken into custody by WICKED agents and imprisoned in WICKED's headquarters. During his imprisonment, Gally felt terribly guilty for killing Chuck, even though he had been under WICKED's control. (WICKED had told Gally he would be killing Thomas, which he was fine with, and thus he had not fought their control.) Gally made several attempts to escape, but was stopped by guards every time. However, a group of spies snuck into the facility. They told Gally that if he acted crazy enough, WICKED would believe he had the Flare and put him in a city somewhere in the United States, where Gally and the spies could meet again and Gally could join them.

Gally later sends a message to Thomas, Newt, Minho, Brenda, and Jorge, telling them to meet them at his apartment in Denver, where he now works for the Right Arm. He explains to them how he escaped and tells them that WICKED is after them and Hans, the man who can get rid of the implants in their brains. He also tells them that Teresa and the rest have been there, and if they wanted to join the Right Arm after finding them, they should come see him.

When Thomas and Brenda later find Vince, the leader of the Right Arm, Gally is there with him, and he assures Vince that Thomas can be trusted. He becomes part of the "army" that takes the Immunes back to WICKED to take it over. However, when the Right Arm is preparing to blow the place up, regardless of any Immunes left in the Mazes, Gally joins Thomas and the rest.

He helps Thomas rescue the rest of the Immunes, going back to the Maze and then fighting against the Grievers and Janson's men before going through the Flat Trans to the last paradise with the Immunes.