Riku liked fairy tales when he was little. He would have his mother read them to him, laughing, repeating some lines and being mock-afraid at others. He always laughed off the evil villain, because the hero was always stronger at the end.
He liked fairy tales when he was little, before he threw them away for sword games and races and tackling other boys into the sand, and making faces at girls about how they weren't strong enough, and anyway if he tried tackling them into the sand they would just run home crying to their mothers.
Fairy tales never left his mind though, because whenever he fought Sora with their wooden swords (or Tidus or Wakka coincidentally) and won, he'd always joke about the fact that if they were thrown into a fairy tale he would always be the hero because he was the only one strong enough.
Occasionally he'd regale them, later, with stories about how he'd be the hero and they'd be his loyal friends, pointing out the princess so he could save her and helping him out. Because friends were better anyway, and a prince with friends was always better than a prince without.
He was right, in a way.
A few years after that, he would be thrown into his own personal fairy tale. He didn't like it much.
By the time Riku found himself in Castle Oblivion he hated fairy tales with a passion rivaled only by Sora's passionate love for the world as a whole, and for friends, and for Kairi.
He hated fairy tales because he knew fairy tales, and although the prince sometimes had friends, there were only three important characters: The Princess, who was lovely and loved and loving and needed to be saved; The Prince, who was brave and loyal and also loved, willing to do anything to protect the innocent; and The Villain, who was ugly and terrible, and who thought only of himself- and who always lost in the end.
He, Sora and Kairi had been thrown into a fairy tale.
He hated them with a passion. Kairi was a beautiful princess, and Sora was her Prince, though his shining armor was… questionable.
And Riku, our dearest 'prince' Riku, knew there was only one role left for him.
Adopted from the deep pain of being abandoned by Sora- because the princess was more important.
'Why wasn't he looking for me?'
If he had known the pain the evil villains had to go through, he never would have made fun of them in those fairy tales.
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Yes, yes, I know Sora didn't abandon Riku. But if you care to remember, that's what he thought for a rather long time, thanks to Maleficent.
This didn't really turn out the way I wanted, but oh well...
And thank you Pink, it's now fixed.