Sephiroth seems satisfied by whatever he sees in Cloud's face - Cloud's not the most expressive man, but neither is Sephiroth. And at least for Sephiroth's part...reading Cloud isn't all that difficult. "Good."

And with that established...he lowers his head again, taking Cloud fully into his mouth again. He hasn't entirely decided on his game plan yet, whether he intends to finish Cloud like this before moving on to other things or simply work him up; he may decide as he goes.