" No one spoke. Thomas stared out the front window in a daze. He’d shot his best friend in the head. Never mind that it was what he’d been asked to do, what Newt had wanted, what he’d pleaded for. Thomas had still pulled the trigger. He looked down, saw that his hands and legs were shaking, and he suddenly felt freezing cold.
“What have I done?” he mumbled, but the others didn’t say a word. "

― James Dashner , The Death Cure (The Maze Runner, #3)