A Cloak of Black (слэш)

All Aegon has ever known is his mother's fear and rage, his father's cold indifference, and his grandfather's blind ambition. Unable to handle eternally falling short of their exceptions, or to face the threat of war on the horizon, he buries himself in his vices in order to cope, and waits for the world to be set aflame by the King's passing.
Until Helaena gives him some advice that changes the course of his life, and the future: try and revive his old bond with his nephew, Jacaerys. If Aegon can convince him that he is no threat, then maybe Rhaenyra and the rest of the realm will believe it too.
And if that means sneaking out to Dragonstone on Sunfyre? Learning more of his eldest sister and her family then he has ever before known? Realizing how kind and brave, smart and maybe even beautiful Jace is? And if those things together, shift the course of the Dance of Dragons, and House Targaryen forever?
Well, who could have foreseen that?
Or:
Aegon accidentally joins the Blacks, falls in love, and fights a war, not necessarily in that order.