.Giffany

.GIFfany is a one-time antagonist from Disney Channel and Disney XD's Gravity Falls and appeared in the episode "Soos and the Real Girl", where she serves as the main antagonist.

Background
.GIFfany is a self-aware Artificial Intelligence created from a Japanese dating simulator called "Romance Academy 7." When the programmers of the game attempted to delete her due to her obsessive programming, she "deleted" them instead, implying that she killed them. Much later, the game she was in found its way to a video game store in Gravity Falls, Oregon.

Personality
.GIFfany comes across as innocent, caring, and friendly towards those she becomes infatuated with. But in actuality she is an extremely paranoid and possessive creature. She is willing to kill people, and the person she loves if she doesn't get her way. .GIFfany pretends to be nice and sweet whenever Soos is around, however this front is impermanent as shown when she quickly becomes furious because Soos wanted to spend time away from her.

Physical appearance
.GIFfany's digital avatar has pale skin and long, straight, pink hair. She wears a large, multicolored bow that resembles a computer ribbon cable. Her eyes are a reddish pink, with highlights that increase as she is complimented by the gamer. She wears a white sailor school uniform with blue trimmings and a pink bow. The collar of the shirt is the same pink, yellow, and blue of her hair bow. She also wears a pleated blue skirt. She wears white thigh-high socks with two pink stripes near the top, with pink shoes. She looks like an anime/manga character.

Role in the series
Soos finds .GIFfany's game inside the store and decides to buy it so that it would help him talk to girls. When Soos interacts with .GIFfany, he immediately becomes addicted to the simulation but doesn't believe it to be real. When Dipper and Mabel come to look for him, they decide to take him to the mall to try to talk to real girls. However, a worried .GIFfany follows him via power lines and finds Soos at the mall where he decides to spend time with her. However, Soos meets a girl named Melody and tries to break up with .GIFfany, which infuriates her to threatening Soos.

Soos promptly pauses her and leaves for his date with Melody with Giffany's CD with the intent of returning it. Unbeknownst to Soos, .GIFfany manages to leave her CD and stalks him at the restaurant.

Once Soos notices her, she takes control of the Hoo-Ha's Jamboree animatronics to stop Soos from leaving. Soos does his best to defend his date and the twins, who have come to supervise, but Giffany ultimately captures both Melody and the twins. .GIFfany corners Soos and tries to persuade him into leaving Melody, saying that real girls are unpredictable and judge him. She attempts to download Soos' brain to the game so they can be together forever.

To the AI's disadvantage, Soos reveals .GIFfany's game disc and throws it in the pizza oven, melting it, and seemingly erasing .GIFfany from existence. In the defictionalized Journal 3, however, it is revealed that .GIFfany managed to escape from her game disc as it was destroyed and ended up in the nearby Fight Fighters arcade machine, where she now tries to make Rumble McSkirmish her new boyfriend.

Trivia

 * .GIFfany's name is a play on the file format .gif and the name Tiffany.
 * Alex Hirsch revealed at BigFest 2016 that .GIFfany is not dead, and still around somewhere. This was confirmed in Journal 3 where it's revealed that she's dating Rumble McSkirmish in the arcade.