"I haven't even really formulated an experiment, yet. There'll have to be some reading first, I expect." He gives a pragmatic shrug. "I wasn't 'warning' you. It simply wouldn't have been a true statement if I'd left off the clause."
"Grubby," Severus explains, distastefully, "right through past the marrow." His eyes go slightly different sizes at the idea of Rus on a leash as several mental images flicker past, culminating with the one where he's toted along like a kite by a giant mastiff. He puts the coaster down with a click of triumph at having navigated that bizarre moment successfully.
He makes a face at Rus and says, "Don't overdo it," which seems a reasonable thing to say in or out of character. "I'm just stiff; I'll do better when I'm limbered up." There: disclaimer given, and if Alf discounts it, that's his own choice. To back the statement up, his rolls his shoulders, which do, quite legitimately, creak and crackle.
Sev says, Really??? He never would have guessed!!!! ;)