His tail lashes behind him, again controlled enough not to smack into anything, but worried? It was closer to what he felt, and doing was precisely his concern. At the moment.

"That something's going to mess up? With a vehicle that pulled us all through an unknown summoning mechanism, keeping all our spirits here until an equally unknown mechanism sends us out, trying to send people back. On purpose. Untested."

He wasn't as much a pessimist as he usually sounded, but this? This was pessimism after having too much information to start indicating how dangerous tethering was, and not just for people like Tidus, who doesn't even have anything he's tethered to beyond the damn train.

"Yes, I'm worried. Are we even going to know if this works?"