Trevor requested and received three starter Pokémon from Professor Sycamore. The day that the three arrive, Xerneas and Yveltal destroy Vaniville Town as part of a battle between them. Trevor is nearly killed during the battle, but Y saves him; however, in the process, Fennekin's pokéball is dropped and lost in the rubble of Vaniville.
Trevor travels with Y, X, Shauna, and Tierno to Aquacorde, where they stay in an inn for the night. The inn is a Team Flare trap, and Trevor, Shauna, and Tierno are stuck inside until X and Chespin blow a hole in the wall of the second floor. Trevor jumps out of the hole and lands in a cushion of bubbles made by Froakie. The five escape and spend the night camping.
Next they arrive at Santalune City, where X and Trevor try to figure out how Mega Evolution works but fail. Viola spots them, and despite Y's decision that they should not trust any strange adults, everyone except Shauna is willing to trust Viola and go to her gym. Shauna runs off and Trevor and the others follow Viola. At her gym, Trevor, Tierno, and Y sort through her photographs of Vaniville's destruction, looking for clues.
Later, Y goes to look for Shauna and returns with her. Trevor later hears a commotion and blearily goes to check it out and sees that Shauna has knocked out Viola with a Honedge. Shauna, possessed by Celosia's Aegislash and Honedge, goes on a rampage, forcing Trevor to dodge. X and Korrina force Celosia to free Shauna and flee.
Next the group goes to Lumiose City. Two masked strangers kidnap the Charmander they found on the route to Lumiose, startling Trevor, but Tierno rescues them. Professor Sycamore then arrives and claims the Charmander. He greets Trevor and then goes off to battle X. While the two fight, Trevor and the others wait in a café for Professor Sycamore's friend Lysandre to fix Trevor's Holo Caster.
When Lysandre arrives, Trevor is shocked to recognize his silhouette from the photos of Vaniville's destruction. Frightened, he hands Lysandre his Holo Caster and whispers to Shauna and Tierno, showing them the photo, but Lysandre overhears and demands to take the photo. His Gyarados, Pyroar, and Mienfoo surround the three, but before they can do any damage, Diantha and Y interfere.
After Lysandre leaves, Y chatters excitedly about meeting a movie star and gives Trevor a playful push. He topples over, fainting from a fever.
Trevor is serious and studious. He is also a good friend, as seen when he tries to help X by getting him a Pokémon from Professor Sycamore. He can also be sensitive and scares easily.
Flabébé has been seen standing beside Trevor.
Trevor is childhood friends with them.