Magic, Mad Science, and Mystery

The Avengers are looking for new members. They go to Hogwarts, UNIT, the Winchesters, the Ponds, Torchwood, the TARDIS, and 221B, then bring them all back. For some, it is a match made in heaven. For others, it is a highway to Hell. Too many characters and pairings to list, but there will be m/m, f/f, m/f, and one m/m/m. Mostly crossover pairings.