This little drabble was written for the prompt First Date, for the Slytherin House. (440 words)
Sirius Black was known as Casanova of his generation. His ability to charm and woo any girl he wanted (except Lily Evans, of course – hey, she was Prongs'!) had in turn both amused and exasperated his friends. However, what most people didn't know, was why he was such a womanizer.
Most, including his friends, thought it simply to be an expression of power he had with his brilliance and charming looks; Slytherins whispered of the disappointment and resentment Black family felt for the oldest son and Heir, and the payback Sirius felt he was giving them by besmirching his family's reputation; Severus would sneer, if asked, that it was simply his ego not allowing him to settle with one girl.
Regulus Arcturus Black knew better.
He knew of the charming ten-year-old girl who waltzed into the 12, Grimmauld Place on November 3rd, 1969. He remembered his brother's star-struck look and his own awe as she proceeded to turn their parents into goo with her eloquence and pedigree, only to turn to Sirius and ask him to dance with her.
A birthday present from the Eisenhardt family, she said as an explanation with a mysterious smile.
Sirius danced with her for two hours straight, never getting tired or letting his eyes leave her face, taking only short breaks to greet other children who came to his birthday party, and even then it was with great reluctance. As the clock struck 10, she parted with Regulus' brother, tears in her big blue eyes, promising him her first date and he returning the sentiment, and left the party to get home. However, she never came home.
Two days later, Annabel Eisenhardt was found dead near the Knockturn Alley, with no signs of violence on her body. Avada Kedavra was the only explanation. The rumor had it, the Dark Lord killed her personally, for refusing to give away her family's secrets.
Sirius never cried for Annabel. He never even went to her funeral. But Regulus knew something died in his brother's heart that day. Something that made him seek out girls who looked like Annabel, talked like Annabel and danced like Annabel, but could never be Annabel. In a way, Regulus guessed, sighing as he saw his brother blatantly flirt with giggling fourth-year Ravenclaw with the similar blue eyes as Annabel – Pandora, was it? - , Sirius was punishing himself, by both breaking and not breaking his promise to the dead girl. Going out on dates with all those girls, but never, ever seeing them for what they were, other than being flawed copies of his beautiful Annabel, the only girl he ever loved.