Barkley appeared once in The Scorch Trials along with Jorge and Brenda after the lightning storm in Crankland/the Scorch. Despite the fact he seems to obey to Jorge, he doesn't approve his decision to help the Gladers, and he doesn't have trust at all to cross the town. He decides to take the leader's place and rigs an explosion at the Underneath entrance.
In spite of his rather advanced age for a Crank, Barkley is tough and veined muscles stretch the sleeves of his shirt. Brenda and Jorge describes him as upset, bossy, more or less paranoid but also at a more advanced stage of the Flare, causing him to lose his mind.