If Diarmuid asks later, it'll be fine. Pharos doesn't really see a reason to hide what he is or what his world is like. He also just doesn't see a reason to elaborate without being asked.

The creatures the other boy describes sound a little like Persona and Shadows, at least in appearance. Though really, they can look like anything so maybe that's not so surprising. "I think I'd like your world too," he decides after a moment of thought, "I wish I could see it."