Gary is a very smart high school student who needed a full ride in order to become an engineer. He is also allergic to wheat and is a virgin (which Sam comically points out calling him a "frustrated virgin"). One day when he and his friends were convening and dabbling with magic, Gary goes into a trance and draws Dean Winchester's face. With this image they heard that there is bounty on this guy. To Gary's luck, Dean and Sam Winchester stop by his work and Gary sees Sam as a way to get close to Dean. So he and his friends knock Sam out, and Gary casts a spell that causes him to switch bodies with Sam.
Gary is amazed with his new "body", and checks out Sam's body in the mirror. Then Dean walks in, and Gary mentions the maid saw the gun, which forces them to leave the hotel. Before they leave, Gary steals all of Dean's cell phones. Gary then asks to drive the Impala, but ends up reversing into a garbage bin. When they arrive in town, Gary realizes that the ghost they were hunting he knows about, which surprises Dean. When they get back in the Impala, Gary tells Dean to turn up the music, which Dean is confused about, but does it anyway.
Gary accompanies Dean to the grave site and enjoys holding the gun. Dean looks concerned again, but Gary denies that anything is wrong. When Dean starts digging the grave, Gary is about to shoot Dean when the ghost attacks. Gary does save Dean though. The two go for a beer and Gary realizes Dean isn't such a bad guy. Later, Gary hooks up with some chick from the bar, and Dean finally realizes that "Sam" isn't Sam.
When Gary returns from his night with the unknown lady, he attempts to kill Dean (after his friends called about his body) only to be knocked out by Dean. Gary is tied up and interrogated by Dean, but a demon who is possessing Nora comes and unties him. The demon offers Gary anything he wants in exchange for Gary meeting with Lucifer and answering "one simple question" with "yes." Gary hesitates before Dean recovers and attacks the demon to no avail with the demon-killing knife. Gary watches the demon beat Dean for a moment before starting an exorcism, enraging the demon who chokes him. However, Dean picks up the exorcism where Gary left off and the two trade lines, eventually exorcising the demon from Nora. Gary then reverses the spell, and he and Sam return to their normal bodies. Dean tells Gary never to perform magic again, or they will come back and kill him. They didn't kill him before, because he is underage.
As they are dropping Gary off, Sam tells him that Nora doesn't like magic, but him. Also that he has a great life. It can be assumed that after this, Gary gives up magic for good. However, Sam secretly admits that Gary's life really does suck.
Powers and Abilities
Gary was a budding and rather weak witch.
- Limited Spell Casting - As a budding witch, Gary had a limited ability to cast spells. However, he wasn't very powerful as shown with his request to a demon to be made "a real witch, a powerful one."
- High Intelligence - Gary is shown to be highly intelligent.
- Automatic writing or Psychography - During an invocation ritual joined to his coven, Gary went into a trance and drew a Dean's sketch.
- Multilingualism - According to Mrs. Frankle, Gary is very talented in languages. He was capable of reading an old leather-bound spell book which was written in others languages.
- Witchcraft Book - The book that he and his coven used to practice witchcraft. It contains detailed articles and images of summoning rituals and body-switching spells, among other things.
- Despite Gary be considered a witch in the series terms, Trevor alleged that he was a warlock.