Another dumb jock. Oops, did I say that out loud? ^^;; No, Tidus isn't all bad. He's a nice guy, a little goofy, pretty insecure about his own abilities, since his father always talked down to him. His idealism is endearing even as it's annoying. He's riled up to no end by Auron's superior attitude and frequently complains about Auron's tendency not to share important information.
I guess I like Tidus only for the reactions he gets out of other people. His relationship with Auron is amusing, and the two are almost always at each other's throats. His developing love for Yuna is sweet--okay, saccharine--but an important part of both of their characters. His friendships with Rikku and Wakka provide a lot of comic relief. His attempts to get along with Kimahri make me laugh. And Lulu's initial distain of him makes me love her even more.
But I have to respect Tidus' determination and strength in fighting Sin. Though he's pretty dang clueless (okay, dumb as a rock), he also fights hard and saves the day. Pretty big deal for a guy with so few brain cells.
"Jecht loved you. He just didn't know how to express it."
"Enough about my old man, okay?"
"I just thought you should know."
At first I thought Auron was treating Tidus a lot like Tidus' father Jecht treated Tidus: coldly, heartlessly, constantly using him as a source of personal amusement. Nevermind whether or not Tidus deserves this--the point is that their relationship is much deeper than that.
Auron almost literally drags Tidus to Spira and dumps him there, not returning until well into the game. Naturally this irks Tidus to no end. He spends a TON of game time complaining about Auron, blaming his situations on Auron, teasing Auron for being such a stick-in-the-mud. How could he know he treated Auron so much like Jecht did?
I think Auron sees a lot of Jecht in Tidus, and that's why he appears so gruff with him. Auron wants Tidus to figure things out for himself, to be strong and do what needs doing. Of course, Tidus doesn't realize what grave danger Spira is in, and what sacrifices Yuna and her guardians are making to save it. Auron seems hesitant to tell Tidus the whole truth. He demands the best of Tidus and probably wants Tidus to work it out on his own. At the same time, I think Auron fears losing him much as he feared losing Jecht.
By showing Tidus how to find the Jecht spheres, Auron seems to almost apologize for Jecht's behavior. Would he go to all this trouble if he were merely fulfilling his responsibilities and didn't care at all about Tidus himself? Auron even goes so far as to play matchmaker with Tidus and Yuna.
This isn't exactly a father-son relationship. Nor is it a yaoi fest, despite the large amounts of Tidus x Auron doujinshi on Ebay (all I can say to that is...blech. And this from a fangirl who generally digs slash). It's like Auron is guiding Tidus throughout the game, and Tidus doesn't really realize all that Auron is doing for him until the end. Not exactly friends, but more than comrades. Though I can't really see them spending time together of their own free will, it seems obvious that they would die for each other. Though of course they'd never admit it, they can really accomplish a lot together...as long as they don't drive each other completely insane first--!