Bellatrix ran her thin fingers through his shaggy black hair, using the leverage to pull him down for another kiss.
"I… have to… hmm… go now! I've… got class…" Sirius protested between kisses.
Reluctantly, Bella let him pull away. "You have a study period first thing this morning - what's the rush?"
"I have to meet Remus before Charms to finish our joint project."
Bellatrix scowled, "I still don't like that you hang out with them."
"Well, like it or not, I do. They're my friends, and I'm not dropping them for you, just as I'm not dropping you for them."
Sirius smirked, knowing he had won the argument. "Besides, today's Friday. Surely you can't begrudge them one study period when I'll be yours for the whole weekend?"
Bellatrix grinned evilly (a trait learned very early on in the Black family). "I just got something new from Knockturn; you can make it up to me tonight with it."
Alright, so maybe 'won' wasn't the proper word, but as Sirius got one final kiss and then scampered to meet with his roommates, he knew he'd return to the Head Girl's room as soon as dinner was over. Win or loss, he was Bellatrix's, as surely as she was his.