In the first Maze Runner film, Chuck had crafted an item he made out of wood as to remember and give to his parents if he ever got out from the Maze. But he is shot in the chest by Gally, and bleeds to death then handed his relic to Thomas for he was grateful to have had him as a friend and Thomas keeps it as a reminder of him.

In Maze Runner: Scorch Trials, we see Thomas going back to the helicopter where he and the Gladers are dropped off the WCKD facility to pick up chuck's relic. Then he hands it to Brenda and tells her the story of how his friend died.