There's no good way to communicate like this, not when David's cock is heavy in his mouth, so Ivan reaches out to take one of David's hands in his, threading his fingers with the other man as his head bobs slowly -- taking him in more each time. The squeeze of the other man's hand is the only reassurance Ivan can give that he won't. Well, that and continuing, as he'd paused the moment David had jerked out the sorry.

The idea that maybe he's edging over into territory he can't come back from that blurs the professional with the personal doesn't occur to him. He's done this before, in some variation, so why should he be concerned? There's no call for that.

Which is probably why Ivan adjusts his head without a second thought so he can take all of Duv in his mouth in one smooth motion without choking or gagging once.