Whatever brakes Sephiroth had been applying to keep himself under some semblance of control, that groan and murmured word cut them. (Not that his already aggressive approach was holding back much.) His movements become more urgent as he presses a leg between Zechs', the hand on Zechs' hip gripping painfully. It's not nearly as rough as Sephiroth could be, not by a long shot, but it's more force than he'd exert if he were under no influence but his own. He's always been acutely aware of how fragile people outside himself, Genesis, and Angeal are.

His coat, Zechs will find to his surprise, is...actually only held closed by a single buckle in the front. Once Zechs undoes it, the coat - pauldrons and all - can simply be pushed off of Sephiroth's shoulders(with his cooperation), leaving him stripped to the waist. He's wearing a belt harness, for some reason, but that should be equally straightforward to remove if Zechs cares to.

His mouth on Zechs' throat, meanwhile, keeps moving. Mostly it's bites - he does seem to have enjoyed the idea of getting to leave his own marks on Zechs - but occasionally there are heated, open-mouthed kisses as well.