Eons before the events of the series, Keyhole was a high school student that was part of a band called the Low Keys and also had a "horrible emo phase.". Later in his life, he was stationed as a guard at the Vault of Infinity, where the universe's secrets are kept, until he was caught trying to "steal his own thoughts" from within his head. Keyhole later indulged in criminal activities before being called together by Bill Cipher, along with the rest of his gang.[3]
Season 2
In "The Last Mabelcorn," the arrival of Keyhole and the rest of Bill's comrades into Gravity Falls' dimension is foreshadowed in Ford's flashback of a conversation with Bill. When Bill mockingly tells Ford that he has betrayed him, Keyhole's laughing silhouette is seen among others in the representation of another dimension projected in the Mindscape.
Keyhole with the rest of Bill's gang as Weirdmageddon begins.
In "Weirdmageddon Part 1," during the cold open, Bill introduces Keyhole with the rest of his friends to the residents of Gravity Falls. Afterwards, on Main Street, Keyhole and the others watch Bill turn Ford into a lifeless golden statue and taunt Dipper before burning the journals. Later in the episode, Keyhole is seen drinking Time Punch with Paci-Fire and enjoying the "V.I.P." party Bill is having at the Fearamid until Time Baby and the Time Paradox Avoidance Enforcement Squadron crash the party. To the demons' delight, Bill vaporizes Time Baby and his squadron. The party then continues as Keyhole and the others rejoice over Time Baby's presumed death.
In "Weirdmageddon 2: Escape From Reality," Keyhole and the rest of Bill's minions attempt to leave Gravity Falls and spread their chaos across the world, but are stopped by an invisible barrier around the town. A short time afterwards, Keyhole informs Bill that Gideon allowed Dipper, Wendy and Soos to enter Mabel'sbubble. Bill is unconcerned, believing that no-one can escape the bubble's temptations, and tells Keyhole to bring him Gideon and take the rest of the day off.
Keyhole being sucked back into the Nightmare Realm as Weirdmageddon ends.
In "Weirdmageddon 3: Take Back The Falls," Keyhole participated in the battle against the Shacktron. Following Bill's defeat, he was sucked back into the Nightmare Realm along with his comrades.
He and 8 Ball make a brief cameo during the tale "Don't Dimention It!", when Mabel falls through dimentions, one of the dimentions she falls through is the Nightmare Realm, he and 8 Ball are standing next to a statue of Bill that reads "HE WAS THE WORST" in their base, with an angry face. This implies that he and 8 Ball probably hated Bill or it was like they were saying he was the best, but since they are evil, they put "He was the worst."
Appearance
Keyhole has an aqua humanoid body and a large forehead with a trio of pink spots on the sides and a large hole resembling a keyhole, hence his name. Additionally, Keyhole has a darker shade of blue around his eyes, a small pink nose and small blue aura.
