Brother and Sister? (An avengers and PJO crossover)

Bucky isn't just the winter soldier. He's also the son of Poseidon. He turned sixteen way before the Great Prophecy, and was never illegal. He met Percy Jackson before the giant war, and is now meeting her after the giant war. What happens when Percy shows up on the avengers compound, and Bucky remembers his little sister?

Also big trigger warning for the entire book. Abuse, death, blood etc. don't read if you'll get a panic attack it's not worth it.