Estinien hadn't actually realized that Cid was from a different time than him and Himeka... how does that work, precisely? Then again, Himeka had told him that Emet-Selch only had memories of their time in the First, though even then, he'd thought that might have something to do with his death.

So it seems less that Cid returned to experience a timeline unseen, so much as he caught up with the rest of them. What purpose is there in that? Had Cid simply forgotten the rest during the transferal?

"Return..." Estinien mumbles, trying to sort all of that out. "From my perspective, that was already in the past. I wonder... could you have arrived with an incomplete memory? Or did you truly return to Eitherys for a time?"

He'd like to believe it's the latter, considering the implication. But it's not something that's easy to be sure of.