A Noctis from a different world. [He gets it, it's confusing. It used to terrify him, the idea that the multiverse was a million million times bigger than he had ever imagined it. But it's... this is the least terrifying part.]

There are infinite amount of worlds, some are really different than each other. Like mine and Ignis', some are really similar right down to having the same people. Small choices make them branch off, so the Noctis who was here before is a different Noctis than the one now, he might remember the exact same things as the first Noctis or his world might be different in a few ways. He might be from a different time, knowing things that have not yet come to pass in a different version of his universe. [He pauses a second, just to check that Gladio is still following]

It's a lot to get used to but it will become less confusing with time. [He's given this speech a lot, he's just glad he no longer has to explain to people that there worlds really are dead along with everyone they had ever known.]