Sephiroth isn't entirely surprised by the question - if anything, he's surprised more people haven't asked - but the phrasing of it has him tilting his head a bit. He's...barely being asked anything specific enough for him to even answer.

"He's a younger version of myself," he says, which really just...reiterates what Cloud apparently already knows. But what is he being asked to explain? "From a period of time immediately after my first deployment as a SOLDIER. Beyond that...you'll need to be more specific."