58 years after World War 2, HYDRA gets an owl with a message. One addressed to the current leader of HYDRA from a Tom Riddle, Jr. HYDRA is invited to tour the British Ministry of Magic. The ministry that has been under Voldemort's control for five years. OR: Harry Potter and Bucky Barnes' Revenge Roadtrip. Top Harry. Harry/Bucky
Instead of going to the Dursley's for the summer after fourth year, Harry Potter stays at Hogwarts. Halfway through the summer, on a quiet walk through the forest, he finds someone lying on the forest floor, bloody, bruised and broken. Someone who does not live on Earth. Someone who has really powerful magic. Harry/Loki. Top Harry.
Once again, Harry James Potter is in the wrong place at the wrong time. Harry/Loki/Thor. COMPLETE.
Harry's life turns upside down when his eyes start to glow red in fifth year. Or: Oliver Queen is not alone when he arrives on the island. (Harry/Oliver)
Adventures in Space
A week or two after defeating Ronan, the Guardians are just finishing up a job on a distant planet when they see a stranger in the Milano. Or well, a stranger to everyone but Peter.
While the Avengers are coping with the loss of Coulson on the helicarrier, Loki gets a rather odd visitor. Tony/Loki. Harry Potter/Steve Rogers.
Sticks and Stones(and Snakes)
After Harry Potter's second year, he asks Aunt Petunia if he can go a reptile summer camp near Central City in the States. She agrees, if only to get rid of him for a few weeks. Coincidentally or not, it's the same camp that Barry Allen is going to. Gen. Pre-series for The Flash.
Strangeness and Charm