The Hydra Problem (PJO/HOO and the Avengers)
All Percy, Annabeth, Jason and Piper wanted to do was have a nice, quiet day celebrating Annabeth's new internship at Stark Industries (Yes, THE Stark Industries), preferably without any monster interference. Instead, Piper was kidnapped by a hydra and now the three demigods have gone on an emergency quest to follow the monster and get their daughter of Aphrodite back. To make matters worse, they seem to have picked up a trio of mortals who have a sudden interest in their, ah, hydra problem.
Steve Rogers was very keen on having a night off, maybe even get in a little time at the gym. But while he was there, he heard a few kids say something very strange. Who are these guys? Why do they keep talking in that strange language that not even Natasha can understand? And do they have anything to do with SHIELD's little Hydra problem?
This isn't your average Heroes of Olympus meet the Avengers crossover. It's really more like a Steve, Natasha, and Clint awkwardly and creepily stalk Piper, Jason, Percy and Annabeth short story. 5 parts; no more, no less. No spoilers for Age of Ultron, though huge ones for the Winter Soldier and Blood of Olympus.
Disclaimer: I don't own any characters, all rights go to Rick Riordan and Marvel. I only own the plot.