Timeline Harry Potter - after Order of the Phoenix. Buffy the Vampire Slayer - after Chosen.
Disclaimer None of these characters belong to me. All Harry Potter related characters, settings etc belong to JK Rowling; all BtVS characters etc belong to Joss Whedon.
Two hours later, Hermione Granger woke up. Her head was sore, but not blindingly so. She had to blink a few times before she realised where she was - half slumped on top of Harry Potter, who was half slumped on her. Disentangling herself, she gently lifted Harry's wrist and saw by his watch it was 5:30 in the morning.
Hermione sighed. She really didn't feel that bad. Maybe it was one of the physical properties of being a Slayer. Or maybe she could just hold her drink very well, she reflected ruefully. Suddenly, she stifled a gasp. She distinctly remembered saying to Harry something about being a Slayer. Oh God. No, he wouldn't remember. She was sure of it.
Cautiously she went up the girls' dormitory and gathered a few things, then crept back down without a sound - Slayer stealth, she thought, too weary to want to forget about these things. Hermione left the common room silently and moved towards the Prefects' bathroom - what she really needed was a nice, long soak.
About an hour after that, Hermione felt rested and refreshed, and smelt faintly of roses. The bath had been extremely relaxing, apart from a small incident with Moaning Myrtle who grumpily asserted she had been asleep in the u-bend before Hermione had arrived.
Being who she was, Hermione regretted very much what had happened the night before, but she'd just felt so - reckless. It was extremely uncharacteristic for her and she found herself wondering if it was part of being a Slayer. Living on the edge. Needless to say, last night would not be repeated. And if Seamus, Dean, Ron or Harry dared to say anything ...
Ron and Harry. Now that was slightly puzzling. Hermione hoped they'd regret their actions too. What they could remember of them - she allowed herself a small smile at this. She could see perhaps why Ron might do it: his friend's birthday, a Friday night, a party ... a typical teenage boy. And Harry the same too, to an extent. But with Sirius' death ...
As she realised she was drawing near to the portrait hole, Hermione's train of thought stopped abruptly. She murmured the password and entered, to find the room a mess and the four boys still comatose. Rolling up her robe sleeves, Hermione pulled out her wand. There was work to be done here.
A few muttered charms cleared the room of incriminating empty bottles, and equally incriminating crumpled parchment - if only Parvati could see that - and made it look half decent. Then she turned her attention to the four boys. Five boys - Neville was still stretched across the cushions.
The bushy haired Gryffindor thought about this for a moment, then left the common room for the second time that morning. Although she ran the risk of bumping into that hellish cat Mrs Norris, it was early enough for her to be out of bed without too many questions.
When she reappeared, Hermione was carrying a tray of steaming coffee. Being early on a Saturday morning, the common room was still empty. She shook each boy awake quickly. At least this bossiness was part of herself, she reflected, as she served the coffee with her most disapproving look.
When Harry and Ron appeared in the common room later that day, Hermione was sat at a table, finishing off her last roll of parchment on a particularly venomous Potions essay, due in that Tuesday. Both boys sat down at the table, without saying a word.
"Hermione ..." Ron began, sharing a guilty look with Harry.
"We're very sorry," Harry continued for him.
"Yeah, we didn't mean to make you feel you had to have some Firewhisky," intercepted Ron.
Harry looked puzzled. "But we did wonder - why did you? I mean, it was a really stupid thing for us to do, but you?"
Hermione opened her mouth. "If I could just get a word in edgeways. No-one forced me to consume that stuff. I just ... Oh, it's too hard to explain."
There was silence for a minute. Then: "How do you both feel anyway?" Hermione said with a smirk.