1. (Avengers/10th Kingdom)
Darcy wasn’t thinking anything of it when she invited Jane, some SHIELD agents, and the Avengers to her cousin’s diner to celebrate her birthday. Sitwell and Coulson would appreciate the food. Plus, in her defense, her cousin Virginia had neglected to mention that a) her deadbeat dad, Darcy’s uncle, hadn’t run off but was actually living in a whole other dimension and b) Virginia’s husband Wolf wasn’t entirely, well, human. When a group of red-cloaked assassins tried to kill Wolf in the middle of the party, however, Darcy found her work life and her family life mingling in some very strange ways.
When Natasha was assigned to investigate the disappearance of Marissa Wiegler, she hadn’t expected to uncover a C.I.A. program far too similar to Department X for her own peace of mind. She certainly hadn’t expected to find someone like Hanna. Now Natasha just had to figure out what to do about her. (Clint’s voice in the back of her head jokingly saying, “But Director Fury, she followed Nat home. Can’t we keep her?” didn’t help matters.)
3. (Avengers/Percy Jackson)Tony had gotten used to the idea of the Norse gods being real and aliens. Finding out about the Greek gods and the fact that to all intents and purposes they’re actual gods? That was a bit harder to take, especially when it seemed as though he was suddenly surrounded by demigods— Hawkeye is the son of Apollo, Darcy the daughter of Hermes, and Maria Hill the daughter of Athena. …Then he discovered Pepper’s mother is Tyche and really lost it.
4. (Avengers/The Pretender)
SHIELD had been trying to get someone into The Centre for years to no avail when Jarod escaped. When someone noticed the pattern of Jarods with identical faces uncovering crimes across the country, Fury sent Natasha to gather intel on him. Fury hadn’t intended for her to join forces with Jarod against the Centre and raze the place to the ground, but he probably should have expected that outcome.
5. (Avengers/Young Justice)
The Justice League is a popular comic book universe in the Marvel ‘verse. When SHIELD discovers that a group of teenagers have decided to take up being superheroes inspired by their comic book heroes, they send the Avengers to talk them out of it. Instead, the Avengers become mentors to the teenagers, with particular bonds between Connor and Natasha, Artemis and Clint, Wally and Bruce, Thor and Kaldur, Dick and Coulson, Megan and Tony, etc.
and one I’m writing:
Officially, SHIELD and the Men in Black didn’t work together. SHIELD handled the big, flashy alien invasions, while the Men in Black handled the more subtle threats and mundane tasks of a planet within a diversely populated universe. Unofficially, however, the two agencies were more inter-related than they seemed.