Originally Posted by gobi no rokubi

As we all know Obito Uchiha was one of Kakashi's teammates when the Fourth Hokage was their Jonin Squad Leader. Shortly before Obito died, he donated one of his eyes to Kakashi whose original eye was left missing.

The Sharingan Eye that Kakashi possesses is indeed Obito's eye, but since Kakashi doesn't have Uchiha blood inside him, the strain of using the Sharingan hurts him somewhat. Over the years Kakashi has used the Sharingan to his advantage and was given the title, "The Copy Ninja of 1,000 Jutsu". He also mastered using the Sharingan Eye as well...

So what really happened to Obito, did he really die or cheat his own death?

Some sources say that he undergone a new identity known as Tobi, a member of the Akatsuki Organization. If you look at Tobi he's wearing a mask with an eye hole referencing the eye that some people think is the eye that Obito gave to Kakashi shortly before he died.

If Obito really did cheat his own death and joined with Akatsuki over the years, why would he betray Konoha like that?

Does he have a grudge against Kakashi? What would it be?