Sephiroth sympathizes with Genesis' impatience, but it's both inconvenient and unnecessary. He intends to give him what he wants quickly enough...but the thrashing just makes it harder.

So, as casually as if he were scruffing a kitten, Sephiroth lifts a hand to grip the back of Genesis' neck. The other goes to his mouth, using his teeth to tug off one of his gloves(which promptly disappears into the same pocket of his coat as the egg). With that done...he lines himself up again and presses into Genesis once more, this time from behind.

He doesn't leave his already restless mate wanting. He immediately establishes a rhythm, this one a bit more controlled than the previous ones but with the thrusts no less deep or strong for that. His ungloved hand, meanwhile, slips around Genesis' waist and between his legs, fingers finding his clit to tease it as he fucks him.