Sirius was beside himself.

Snape’s sister. Of all the girls in Hogwarts, it had to be Snape’s sister—quiet, quick-witted, with eyes like molten ink and that sneaky, sardonic smile that made his stomach flip. Merlin must be having a good laugh. It was like a cosmic joke, really. She didn’t even seem to notice him most of the time, and if she did, it was only to throw a smirk his way before turning back to whatever she was reading, thoroughly unimpressed. And Sirius, who usually wore cocky confidence like a second skin, was utterly lost for words.

The others had noticed, of course. James teased him endlessly about it. “Moony, do you see this? Pads, smitten by a Snape. A Snape. What’s the world coming to?” Remus merely gave him that knowing, sympathetic look of his, and Peter snickered as if he were part of the greatest prank Hogwarts had ever seen.

It was when he found himself peeking into the library, again, just to see if she was there, that Sirius knew he’d completely lost it. He didn’t even like the library! Books made his head hurt, but there he was, lurking behind a row of ancient, dusty tomes, trying to catch a glimpse of her. She sat at her usual corner, brow furrowed over a thick book, and all he could do was stare like a besotted fool.

She looked up once, and Merlin help him, he panicked and knocked over half a shelf of books. She raised an eyebrow, probably wondering why on earth Sirius, of all people, was even in the library. And Sirius could do nothing but blush like a first-year. He, Sirius—the most reckless, smooth-talking Marauder—reduced to a stammering mess.

"Alright, Black?" she asked, voice laced with faint amusement.

“Brilliant,” he managed, his heart pounding. He wanted to say something clever, something that’d make her smile, but all he did was nod like an idiot as she returned to her book.

It was official. He was doomed. Sirius was infatuated with a Snape. And Merlin’s beard, he was absolutely, hopelessly done for.