Right now, I'm most towards the Izuna theory, but that's not why i'm posting.
I'm a bit lost about what Tobi said to Kakashi.
"You're just words and no actions! What someone like you says is worth nothing! It's too late to regret. Reality is just cruelly moving forward."
Maybe I don't have my facts straight, but I don't understand why Tobi is so pissed towards Kakashi. No malicious villain like Tobi should have that kind of emotional tying. Nagato did, but it showed that he had hope in becoming good, and Naruto was that hope for him (cheesy LOL)
Tobi knows almost everything about Kakashi, and always makes deep eye contact with him in every meeting. He clearly has some connection to Kakashi, and knows about his regret in not being able to protect Rin when he promised to.
This hints (I'm not saying it proves anything) that Tobi = Obito.
Obito loved Rin, and would do anything for her.
Also, Kakashi promised to protect Rin, but wasn't able to, and Obito would be pretty pissed about that if he was alive.
And he also mentioned to Kakashi when he was alive that abandoning your friends makes you worse than scum. That was a principle he lived by. Kakashi was named the Hero of the Sharingan, but, to Obito, that title probably meant nothing, because Kakashi couldn't even save his friend and Obito's love.
But the thing is: Obito would most likely work things out with Kakashi if he were alive, not have murderous intent. These are malicious thoughts that would be probably rooted deep inside Obito if he were still alive (ugh i've repeated that a lot of times, haven't I?). Everyone - all of us - have malicious thoughts that we never reveal. Unless all our thoughts disappeared and we were resorted to primal instinct, then maybe.
What doesn't make sense is the fact that Obito would never want to cause global domination, unless he was brainwashed or the theories that I've read on the forum about Madara being sensei and Obito being pupil (The person who fought Minato in the past may have not been Tobi. It could've been Madara who passed his ideals to his pupil, who is the Tobi we see today.)
He also said that same chapter that he got the eye at the fight at the Kannabi Bridge; he didn't say that it was his eye from the start.
It's weird. Somehow I'm thinking Tobi has identity crisis or something.

He has the emotional connection to Kakashi and his regrets, like Obito would have, but he also has the plans to destroy the entire world, well, inflict Infinite Tsukuyomi, which Obito wouldn't have. It just doesn't fit together. I almost think that mentally, one half of Tobi is Obito and the other half of Tobi is Madara, who would want to destroy the world because of the discrimination that the Uchiha faced.
Obito would never show such malicious intent to Kakashi, but Madara would. It's almost like their thoughts, emotions, and experiences are mixing together and making a new personality which is Tobi. (This could make sense if you consider the sensei-pupil theory)
But again, this might be the worst theory ever.. Just what thoughts I'm having to make sense of this O.O
There are so many things going on; can't wait until it's all made sense of. :sy: