He'd known the second he'd seen them talking together in the infirmary; the second he'd whipped around as though caught in the act of stealing. He had been caught in the act of stealing, but that didn't mean he'd returned what he'd stolen.
He began to notice the very next day what effect it had on both of them. Sirius smiled more, he was smiling all the time. At breakfast Aislin and Demi hadn't sat at their usual place at the end of the table, instead they sat next to Sirius. Remus noticed the shiver that had gone through her and the smile smiled that emerged on her lips when Sirius had accidentally on purpose grazed her arm with his hand while reaching for a piece of toast. The same kind of touch he'd given her days ago and received no reaction from.
In class, they would sit together. They'd write notes to each other on the same piece of paper and lean in to each other as though to look at each other's notes. After class they sat together close on the couch by the fire, holding hands. They weren't making out like he had with his last girlfriend, but he could tell, by the look in his eyes and the way that she was biting her lip, that it wasn't very far from either of their minds.
He'd gone upstairs without a word and now he was sitting on his bed in the dark, torn between crying into his pillow and storming back down into the Common Room to beat the life out of Sirius for his betrayal. Instead, he did nothing; he just sat in the dark and stared out the window, fuming inside. He wondered, cruelly, for how long Aislin could hold Sirius' attention. One week? Two? A month maybe? Sirius had never stayed in a relationship for longer than a month.
Then he wondered why, in the name of Merlin, hadn't he asked her first? He'd been alone with her for a day and a night. She'd been pressed against his body for 28 hours and he'd never just told her how he felt. The closest he got to it was saying something about awkward secrets.
The Hogsmeade weekend came, but he stayed at the school. He didn't want to think about what he was missing out on, and he didn't want to think about what they were doing. After a lonely supper, most people hadn't come back from the village yet, he made his was to the library. He needed to find a good book to keep his mind off them.
It was past midnight when he finally decided to pack it in for the evening. He'd read through an entire volume detailing the Goblin Wars. Even the book managed to come off more exciting than Professor Binns' History of Magic class. He made his way back to the Common Room, but as he crawled in through the portrait hole, he stopped dead in his tracks.
Sirius had pinned Aislin against the wall and was kissing her ferociously while his hands ravaged around her body; under her shirt, her back, her face. Aislin was as bad, her hands tangled in his hair or running across his back. Remus' mind was blank for a moment before he silently backed out of the room and closed the portrait hole.
"Well, come on boy, are you going in or not?" The Fat Lady demanded from her regal place in the portrait.
Remus ignored her and fled back down the hall. He was completely numb. Of course, he'd known this would happen, had even suspected it happened whenever he'd left the Common Room at night. But he hadn't been ready for the shock of it; for the blinding jealousy or the sickening feeling in the pit of his stomach. It tasted like betrayal, jealously and rage all at the same time.
He ended up collapsing in some corridor on the second floor as far away from the Gryffindor Common Room as he could. How could Sirius have done this to him? Weren't they best friends? How could he? Would he always only be second best?
