It's always good to see friendly faces - and here he spots Romeo (even hears him, him and his little crew, first) doing what he does best, at the front of a group where he fits in well. Tidus has his own back to a wall, taking a rest; and in the process of wondering if he should move elsewhere, use Gibs to help with the water supply in a less direct manner than he usually would.

Hey, I can make fresh water appear from nowhere! -- Yeah, like that'd go down great.

That had been on his mind, anyway, until the aforementioned boy and his crew - and Tidus looks down the rest of the cavern, humming thoughtfully.

"Don't think so... but you can leave 'em around so people can find them. You got enough?"

Maybe that wouldn't be smart if they were limited, but with what's in Romeo's arms, he looks prepared!