12 Grimmauld Place was a gloomy place at the best of times, and this was far from the best of times. There was a war on, after all, and half the time it was crammed full of people. Then again, only Ron Weasley was actually used to dealing with crowded environs. Potter and Granger and even Snape were only children, and McGonagall was full of a cat's definition of personal space. Worse, Weasley and Granger were fighting, again. That would have been bad enough, if it wasn't effecting Potter whose control over his emotions was notably worse than usual. A nd the noise itself, if nothing else, was irritating Snape.
As Snape appeared at the top of the ghastly, rickety staircase, his quick eyes noted that Granger was bawling her eyes out, her entire face concealed by her bushy hair, as she buried her face in the couch. And where was Ron? Probably sulking, as was his wont. Snape, who never cared to pry about personal matters, wasn't even entirely sure that they were dating, rather than simply two sulky, petulant teenagers who fancy each other far too much to actually tell each other about their feelings. Not that I'd know anything about that, of course. At least I was quiet about it!
In Snape's chillest tone, he purred, razors peeking out of every word, "Ah, Miss Granger. One would have thought you would have chosen better than Ronald Weasley. In fact, you already have."
Hermione, always quick to jump to a mystery - thus serving as an effective distraction from drowning the couch in lacrymony, raised her head. Swallowing a moment or two, and wiping her eyes, some instinct of hers demanding composure when talking to a Professor, no doubt. Hermione Granger asked levely, "Why, what do you mean, Professor Snape?"
"Why, did no one tell you you're engaged?" Snape asked, his riposte striking home far harsher than intended - and that was saying something, as Snape was not known for mincing words.
Hermione Granger had got quite pale, her back stiffening, as she went through pages of memories, neatly stored in books in her mind. "No, I can't say that anyone's mentioned it..."
Abruptly, Snape was recalculating. Had he been in less of a laconic mood (or not positioned expertly at the top of the stairs, and reluctant to give up the high ground to a potentially question-spouting student), he might have paced. Things were snapping into place - nothing he knew of Granger would give him the impression that she would cheat, particularly without trying to meet her intended first. Reluctantly, he came to the simple, if cutting, conclusion that she couldn't have known.
Absentmindedly, almost idly, Professor Snape said to her, simply, "You might ask your parents." He then waited until her eyes lit up (it was just a moment, after all), and her mouth opened, teeming with unspoken questions, before he said, "I'm afraid I have business of a personal nature to attend to. If you will excuse me..." I'd better remind the Muggle Grangers of what I told Mrs. Granger, years upon years ago. If Hermione confronts her parents, and they know nothing, this will become even more difficult.
Hermione's mouth snapped shut, her hands fumbling for a piece of paper, her fingers closing down on a pen. What was going on, and what was she supposed to do? Nearly unnoticed, Professor Snape strode down the stairs, his robes billowing impressively as he exited the house entirely. Moments later, in an abandoned ally, he apparated away to the Granger's residence.
[a/n: read and review! Severus Snape is a great plot device. For such a sneaky snake, one is almost surprised he let something this big slip through his thin, pursed lips.]