"Gods Severus!" Lupin looked up from his task in mock horror at Snape "It's like Forte Knox!" Snape sneered. Gently. In a way which Lupin had learnt was affectionate. Honestly.
"Enjoying yourself?" he asked dryly. "I can always assist you..." he reached as if to take over, but had his hands slapped away.
"No! I want to! Do you know how long I've thought about undoing these blasted buttons?!? Funny though, in my mind they always seemed to just… undo…"
"I'm not entirely sure I like the fact that my buttons have been 'un-doing' in your thoughts. I suppose this is another one of those things I should take as a compliment?"
"Most certainly. There!" he cried, triumphantly, "done! Now…" his face fell as he realised he was not quite done yet. Under the jacket was a firmly buttoned shirt, and wrapped neatly around the neck, a black silk cravat. Lupin sighed.
"Why do you insist on wearing all this? I've never known anyone dress so…"
"…extravagantly?" he finished lamely, flashing a lopsided grin at the scowl facing him.
"I dress as is practical and appropriate to a Potions Master. I can assure you, I am a lot better at buttons."
Snape lifted the corner of his mouth in a demi-smile, and with a flick of his fingers and soundlessly moved lips made all the buttons on his shirt undo in one motion.
"Show off." said Lupin, nether the less pleased to not have to keep going, he was getting cramp. "I've never undone a cravat before…"
"Then please, allow me."
Lupin watched as Snape's long, lithe fingers deftly pulled the knots undone, and barely suppressed a shiver at the whisper of silk on skin.
"You should wear one some day. Make you look a little less, bedraggled." The words were meant kindly enough, and Lupin had long grown immune to the upfront and direct manner. He couldn't help but tease in reply, though he knew there was a good chance it would be taken the wrong way and Snape's humour would, as normal, fail him.
"OK, Guilderoy." As expected, the smile turned to a scowl and Snape moved his hand toward his shirt,
"I can re-do them just as fast, Wolf."
"Not bloody likely! I spent a good amount of time getting through your wrapping, there's no way you're doing it up again!" Just to make sure, he grabbed the open shirt and pulled it off Snape's shoulders, leaving him bare chested with the dangling cravat around his neck. As he started to pull this down too, Snape twitched and his lips curled. Much to Lupins delight, he let out a sudden bark of laughter, instantly trying to cover it up with a snarl. Again, he actually laughed! Lupin was in heaven, triumphantly shouting;
"You're ticklish! Oh how wonderful!"
"Stop!" Snape by now was practically hysterical as Lupin changed his attack plan to cover chest and arms with the experienced fingers of a seasoned tickler.
'Dear god' thought Snape, 'if the students hear of this…" as he ran across the room and attempted to hide in the bathroom, where he was pursued and tickled to within an inch of his life.