Being raised as a member of The Noble and Most Ancient House of Black, Regulus was never allowed to fail.
He was taught to be perfect. The perfect son, perfect brother, perfect husband.
He never really got the hang of it, though.
Regulus hated himself. He hated that he was so sodding stupid, he hated that he self-sabotaged and never let himself have good things, the things he wanted. For all he wanted was to have James Potter. And he liked to think that he had him, even for a moment.
But what he wanted didn’t matter, all that mattered was what his mother wants, what his cousins want, what the House of Black wants.
He could never be perfect, like his mother wanted him to be. So he settled for being perfect on the outside.
And so he became the image of wealth among the Slytherins; The Slytherin Prince. He uses ridiculously expensive french perfumes, and his curls are always neat and tamed, and his nails are always clean, and his dormitory is known for being the tidiest in all Slytherin.
None of that matters, though. None of that matters when he sees him.
The first time Regulus Black sees James Potter kissing Lily Evans, he almost loses it.
He shouldn’t have been surprised, really. James would always go back to Evans, in the end. He liked her from first to fifth year, after all. Of course, he dated Regulus during his sixth year, but now he came back to Evans, and she finally gave him a chance and went out with him. Regulus doesn’t even know why James liked him during sixth year. Well, James probably thought being by his side was a change from the old routine of Evans, Evans, Evans.
He couldn’t do anything, however. They were together and in love, and he was alone, crying himself to sleep because he knows that James would always love her. James, being the perfect dork he is, would love her until the day he died, and even after that he would find a way to love her in the afterlife, if there really is one.
Regulus would never have James’ heart. He never had it to begin with, he realised. He would never have James’ love to keep, would never wake up to kisses and steaming tea and hot showers and cuddles, he would never have James Potter, the man who was more Sun than Human. Regulus would spend his life alone, waiting for him like a lonesome queen.
And now, watching the Gryffindor Power Couple finally getting together, Regulus couldn’t help realising that, all this time, he was The Other Woman.