A mute!siren!Bucky and skinny!Steve AU. You can find this story on AO3 and FF.net Rated T for some descriptions of violence and gore.

AKA: Percy Adopts Everything WARNING! YAOI IS IN THIS STORY! (Yaoi = Boy x Boy) Tony/Percy/Bucky In this story, Percy is nineteen, Tony is twenty four, and Bucky is twenty six

She first saw him when she was 22 years old, and injured on a mission. He was 10 years old, and visiting an aquarium. Percy Jackson looked into Natasha Romanoff's weary but determined eyes, and decided to help her. And so, he pulled a lever, spilling his class and her enemies into a tank. That was not the last she saw of him. By the time several years pass, the two green-eyed siblings by bond will be known as heroes, albeit of different worlds. Perhaps they don't know everything about each other. But they do know that they will always have each other's backs. He helps her out when her missions don't go the way they planned, which doesn't happen too often. She teaches him how to be a good spy, although that isn't the intention when they start the lessons. And they become very close, just as close as true siblings, in fact. So when Natasha finds herself in a complicated position during the Avengers' Civil War, Percy decides to interfere. And the Avengers are extremely surprised when they meet Natasha's younger brother. Plans are made and set in motion, alliances are completely misconstrued, friendships are tested and broken, and the two siblings find themselves on their own side against the world. However, there's something bigger in the works for the Avengers, and they'll need all the help they can get to face it. Including the two green-eyed siblings in everything but blood. This is largely Marvel canon compliant up until Captain America: Civil War, with Percy's interaction with Natasha being a background to the PJO books. Cover by @cajoling - she's awesome, honestly I'd check out her work as well lol

Set after Captain America: The Winter Soldier. Bucky is lost, without a purpose and brainwashed within an inch of his life. S.H.I.E.L.D and Hydra have both fallen and without anyone to stop him, Bucky intends to find out who he is - or who he was - before Hydra took away every last inch of him. Steve is left recovering from the catastrophe, but knows that Bucky is still out there, and that Bucky needs his help. Steve will do everything in his power to help his best friend find out who he is again. How far would you go to help your friend recover their mind? How long would you try for? Steve knows it isn't going to be easy, and wants to set Bucky on the road to recovery; but confusion and nostalgia hides around every corner. If Bucky is to find himself once again, Steve is going to have to face some hard truths about how he lost his friend and see him through every step of the way as he recovers, seeing him through the good times, and the bad. They might soon realise that the question "Who am I?" carries so much more than a name and a face.