His brows raise at big brother, but if he has anything to say, Tidus doesn't go for it. Watching Seto's move to remember more how to play before making his own move.

"How about what'll be fun? I've never planned a birthday before, let alone been a big brother. I figured I'd see what they all like to eat, buy 'em something they might like for a present, and hope it works out. They all know each other, so I don't think they'll mind."

Maybe it's less a birthday at that point than just a special treat, but hey, whatever. Long as everyone has fun.