Gaius closed his eyes, giving a soft purr of pleasure at the kiss Sirius gave him, then opened them again with a chuckle as Sirius' words sank in. The Hufflepuff disappeared with alacrity, no doubt to inform her classmates that Professor Blank was quite naughty, not that Gaius minded. He was subjected to enough student snogging in the corridors, after all, and turn about was fair play.
He waved the door closed - castle magic of that sort still functioned, thank Merlin - and sighed, his mood becoming more somber. "If only the meeting were going to be solemn, rather than grim," he murmured, then released Sirius with a last squeeze. "Here, we can go out through my Floo, and no one need know where we're headed." With that he turned toward the hearth, gesturing Sirius to precede him.