"It'd be useful to see where things might go wrong," he offers.
Rus gives a snerk himself, though he's not nearly as good at it. "I know." He thinks for a moment then he bursts out laughing. "Oh Severus! Did you think I meant that literally?" He chuckles again. "The idea of you having me on a leash!" He can't help but laugh some more.
"I'd be careful," he protests. Though he can't help but think some sort of demonstration might do Alf a world of good. "Suit yourself," Rus shrugs, also nodding at the refill. "Yes, another bottle, and when you come back, you can fill us in on the details of your little scheme," he informs Alf brightly. "He would have been in Slytherin you know," he mutters to Severus as Alf hurries away to the bar. "We can use that to our advantage."