Divergence
Adrien, a teen model, sheltered by his abusive father, is given the chances of a lifetime in the forms of becoming a superhero called Chat Noir to fight against a villain named Hawk Moth, and going to school like a normal kid for the first time in his life.
Along the way, he learns the ways of the world and develops new friendships, including Nino, Kagami, and Luka, who become his closest friends as time goes on. He even falls in love with his mysterious partner, Ladybug, who is not interested in him that way but is still an important person in his life nevertheless.
When everything he's come to know at this point takes an unexpected turn, bonds are tested and changed in never before imagined ways as Adrien searches for the right thing to do, and learns to accept himself in the process.
(Basically a fix-it fanfic of Miraculous Ladybug, in which Adrien is the main protagonist, and characters besides Marinette are allowed to have screen time and develop).