Wander over Foster's AU One-Shot by Soniana252 (also available on its Archive of Our Own page here) is a crossover fanfic between Wander over Yonder and Foster's Home for Imaginary Friends. It revolves around Wander turning up at Foster's while he's stuck on Earth.
One day, Coco brings an injured and unconscious Wander back home to Foster's Home for Imaginary Friends. He had appeared in the backyard and, due to his inhuman looks, it was assumed that he was an abandoned Imaginary Friend. Bloo soon becomes jealous of Wander's charismatic nature and devises a plan to make himself the center of attention again.
While investigating Wander, Bloo makes an amazing discovery: Wander is an alien! Too bad no one believes Bloo.
Wander over Foster's AU One-Shot provides examples of:
- 100% Adoration Rating: Wander is loved around the house for his personality and because he is always lending a hand.
- Birds of a Feather: Wander and Wilt's similarly polite natures make them easy friends.
- Break the Cutie: Downplayed with Wander. Being away from Sylvia takes a toll on the usually jovial fellow, but he doesn't completely break from sorrow. He instead becomes friends with others at Foster's.
- Cassandra Truth: No one believes Bloo when he says that Wander is an alien. Unlike his other conspiracy theories, this one is true.
- Crossover: Between the two cartoons Wander over Yonder and Foster's Home for Imaginary Friends.
- Major Injury Underreaction: This is Wander's reply to Frankie's concern over him. He has enough injuries to be covered in bandages, but he says it's "just a scratch".
- Mistaken for Aliens: Inverted. Wander is an alien, but no one but Bloo believes him. They just think he's an abandoned imaginary friend who thinks he a alien.
- Mistaken for Spies: Bloo initially theorizes that Wander is a spy for alien invaders. The part about Wander being an alien is the only accurate part of the theory.
- Mysterious Past: Invoked. At Foster's, imaginary friend's pasts aren't often dwelled on. It's considered rude to question someone on why they're at Foster's.
- Oh My Gods!: Wander uses the term "Oh my grop".
- Paper-Thin Disguise: Bloo's "investor disguise" consists of his typical enormous coat and sunglasses.
- Stock "Yuck!": Bloo is disgusted by Wander's vegetarian pizza with fruit as a topping.
- Suspiciously Specific Denial: The text notes that Bloo is looking for a room that isn't too dark at night, but not because he's afraid of the dark.