Everyone acts like "people" do.
There are quite many of those.

cloud held in his emotion sometimes, went crazy at other times, and just had sort of an aura around him that made me feel like he was someone i actually knew.
terra held in her emotion sometimes, went crazy at other times, and just had sort of an aura around her that made me feel like she was someone i actually knew.
tidus held in his emotion sometimes, went crazy at other times, and just had sort of an aura around him that made me feel like he was someone i actually knew.
zidane held in his emotion sometimes, went crazy at other times, and just had sort of an aura around him that made me feel like he was someone i actually knew.
squall held in his emotion sometimes, went crazy at other times, and just had sort of an aura around him that made me feel like he was someone i actually knew.

Everyone. And I don't think Tidus is in any way "more real" than the rest of them. They are simply different. Tidus whines and screams his feelings for you, so he seems to feel "more" whatever.

I'm a nice person, by the way. :fpcow: