The Blood Phoenix 6: A Captain America: The Winter Soldier Fanfiction

She is an Avenger.
Adelaide Lehnsherr-Xavier is, after New York, a official Avenger. Teaming up with SHIELD, Agent Natasha Romanoff and Captain America, or her brother figure/potential boyfriend Steven Grant Rogers, she fights against injustice.
But she struggles to admit her feelings about Steve to him. The only one that she confides in for her feelings is Natasha, one of her oldest friends on the team.

But a reminder of her past comes back to haunt her... as well as the organisation who made him what he is... and who gave her wings to fly...