Sephiroth was content to walk along with them, his mind still on their situation versus settling on any one real thing. He was content enough that he had surprised them or so he thought. In the end, it didn't matter.

"She is fine but weakened by this Head Doctor and this place. She is pleased that we have made progress and wishes us well for tonight. There was a question about some woman named 'Inara Serra'. I know it is the name of one of the 'patients' here, but nothing beyond that. I felt bad for disappointing her when she was so eager. Perhaps you two know more?"

It wasn't beyond Sephiroth to use what lever he had against parts of himself. They were, after all, part of himself. The woman hadn't fled from him this morning or been offensive. Therefore, she couldn't be human, could she? Given that these two had been here longer, perhaps they knew more than he did.