Sirius rather liked that idea - Remus not able to help himself. Moony was fucking sexy, for starters. But he was always in such control of himself that him letting go - him losing control and giving in to pleasure and fucking and whatever else... it was insanely hot. Sirius liked trying to make that happen over and over and over. And pushing some of the bounds a bit too but only if Remus liked it.
At Remus's denial, Sirius gave him a look. "We are stubborn sons of bitches, Remus, but when you really really really want your way, you just won't stop until you get it...until you've controlled both of us," Sirius stated. It was true. It didn't happen often. But it was true. Controlling him or James, much less both, wasn't easy.