I'll agree that Kyuubi changed faster than Sasuke.
I attribute it to the Kyuubi being the more mature of the two, plus he isn't batshit insane.
Kyuubi is a dick and with good reason, but he knows what type of person Naruto is, so he knows he actually means the stuff he says and is mature enough to accept the olive branch.
Sasuke is a brat lashing out (I could have put it in kinder more accurate terms, but that does the trick) on top of being insane.
So of course it is harder to reason with him.
There is more to this than that.Originally Posted by The Drunkard Kid
Mainly because of Lee.
The whole Loser thing boils down to 'regardless of how strong you are a loser is a loser. Fate will conspire against you and make you lose'.
I mean really, Lee was the second strongest in the exam, his point makes no sense otherwise.
Edit: Also Naruto is not the kid of the prophesy until after Jiraya makes him the kid of the prophesy, so he wasn't at the time.
Edit2: Bloodline also apparently didn't matter to Neji, because Hinata was classified as a loser. Hinata as in his superior in regards to birth.
Edit 3: Stupid teenagers and their half baked philosophies...