Disclaimer: I do not own Harry Potter.
By Silver Sailor Ganymede
Sirius Black was not the type to think before he acted. He had made sure to be sorted into Gryffindor to escape from his family without really thinking of the consequences. He had run away from home to James' without ever thinking that one day the Potters might stop accepting him (though of course they never did). He had tried to feed Severus Snape to a werewolf without thinking about what the repercussions would be – either for him personally or for the werewolf, who happened to be one of his closest friends.
No, Sirius Black was not the type to think before he acted – except where it came to Marlene McKinnon, though some people wouldn't have called that thinking at all. They would have called him a tongue-tied, lovesick young man who lacked the true Gryffindor courage to go after what he wanted. He wasn't like James was with Lily. In fact it was nothing like James' and Lily's situation had been – Marlene had been two years ahead of him in school, a Ravenclaw, and it was only during their time with the Order of the Phoenix that he had come to notice her at all.
When he saw her for the first time, he wondered how he could never have noticed her before. Her hair wasn't quite as red as Lily's but it was still a striking colour and was longer and wavier than any he'd ever seen. She had the sharp wit and intelligence of a Ravenclaw coupled with the bravery of a Gryffindor, the perfect combination of traits for a trainee Auror – the perfect combination of traits for anyone, in Sirius' mind. She always smiled (she had the most beautiful smile) and it made Sirius' heart stop when he saw it, but he couldn't bring himself to speak to her; she was too beautiful, too perfect. He had to be cautious; if he charged in thoughtlessly like he usually did then he'd stand no chance at all.
Then one day, when all the Order's business had been dealt with for the moment, Marlene had smiled at him from across the room. At him: not at James, not at Lily, not at the group as a whole – at him. That was when Sirius made up his mind to speak to her the next time he saw her, when he made up his mind that he wasn't going to be cautious any more.
Two days later she was dead