I'm thinking maybe it's danzo who controlled Obito. All right just here me out... Danzo had a yamanaka as his right hand man(Fuu). He also had KA(Shisui's genjutsu that can control you without you even knowing), in addition he had the motive. He was an extremist and was willing to do anything for peace even hypnotize people. I know you're thinking then why would he kill danzo...that's because he doesen't know he's being controlled by danzo so he kills him to further his goals. I also have a theory as to the white stuff that came out of his arm. Danzo might have used some of Hashi's cells to revive obito after the cave in OR he could have created white zetsu with orochimaru. It was said that they worked together sometimes. Maybe they created zetsu THEN used him to revive obito.
