Is she talking about when they met the first day on the platform? That's where Tidus's mind goes--that she owes him for kinda nearly zapping him then with lightning, right?--and so he's neutral to it, easily accepts her company with an "Alright," his mind more on the former talk.

There's still some of this sewer to get through. At least the rats haven't all be attracted at once by their noise. Tidus keeps his eyes ahead, using his light as a guide.

"Are you looking to buy something?"