The door swings open at his rap, because the last visitor hadn't quite closed it properly, and Severus had been feeling more busy (and ill) than paranoid, for once, and hadn't gotten up to fix it. So it opens, on a skeletal and pale young man with a much-broken nose and heavily bandaged throat, black hair pulled back, in a slate blue jumper that looks fair to fall off him. He's sitting on the sofa with Minerva's Gryffindor blanket about his shoulders (it was what was available, she said, and he didn't quite have the gall to do anything about it while so completely her guest), the red of it almost banishes his sallowness. He has a glass of greeny-brown sludge by him, placidly reflecting unnatural golden shimmers where the light hits it, and is engaged in listing flowers and their meanings, with the occasional idle sketch of one.
He looks up curiously, blinks dark eyes to see someone who's clearly a Black. A more cautious look shows him eyes more in Regulus's style than any of the family lunatics, so his tone, apart from being a rather awful rasp, even after he's taken a drink from his glass, is mostly curious as he says, "The Professor's not back yet, can I help you?"