Ok, i have a special theory in Naruto and it is....
THEORY:
Kakashi is actually The Fourth ( Yondaime )
WHAT SPEAKS FOR:
* Let his hair grow out a bit, color it gray, put a forehead protector on his head and that thing on his mouth and here ya go: Yondaime
WHAT SPEAKS AGAINST:
* His rivalty against Gai Sensei
THEORY STORY:
During the great battle against kyubi, Yondaime didnt sacrificed his own life but he was seriously injured and he had lost one eye. He went to the Uchiha clan wich had just got a new member: sasuke. Yondaime got an eye from an dying uchiha member and on his way back to Konoha Village, he realized with his current strength he could impossible stay as Hokage anymore so he disguised himself as a ninja who mysteriously dissapeared one month ago outside konoha: Hatake Kakashi. His returning (fake returning) was unexpected but Kakashi (fake) continued his missions as a jounin and requested Hokage-sama (3rd) to look over Naruto because the fox demon was sealed into him and Yondaimes job was to prevent the fox demon from reappear outside Narutos body. Because Yondaime didnt know Kakashi he told the 3rd that he lost his memory after the dissapearing. That also explains why he refused to talk to Naruto, Sasuke and Sakura about his hobbies etc in the beginning of the manga/anime.
So what do you think?