He's really looking at her blankly now, and was there something he said? Too confused to follow her, unless there's something forward about calling a younger girl a lil' sis. Or maybe she's trying to say he should just call her whatever he wants?

Huh.

It takes him a good second to say anything, though he feels as way lost as he did a few seconds ago...

"Well-- sure. I don't mind us being friends." What did younger kids call older guys that weren't uncle or gramps? Well- "You can call me whatever you want! Or just Tidus, if you don't do nicknames."