So...
We found out why Obito became who he was. It turns out there was a Spiral Zetsu being that Obito "wore" so he could save Kakashi and Rin.
If the Databook says that his name is Tobi then Obito simply "borrowed" the name as such so no one knew he was actually Obito.
Obito (as his Tobi alias) then said he was Madara to strike fear and give himself a leverage above other people. I'm not sure if Obito was wearing Tobi's body (Or better said, Sprial Zetu's body) all this time, but I thought it was pretty obvious that the name Tobi was simply a cover-up for Obito the whole time.
Even if it was shown that Tobi was still alive right up until the end
Bottom panels
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So just to recap:
-I supposed white zetsus can be integrated without the person knowing it but..
-Obito knew about Spiral Zetsu's (Tobi's) existence and wore "him" with full knowledge of his existence, therefore Obito must've intentionally integrated "Tobi" into himself or he would've at least be aware of him and stay away from him
Top-left panel of Obito's memory wearing "Tobi" with his face revealed. Then, obviously, Obito actually using his Tobi alias pretending to be Madara to strike fear upon Nagato.
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-I don't understand your last few points but let's not forget that Zetsu literally knowns everything. Zetsu can call anyone stupid because he can, not because Zetsu would know them better.. Idk.
I have to make this point because otherwise I'm gonna explode, lol:
I remember vividly someone mentioning Tobi and his Awakening from the game Naruto: UNS 2 and how much his personality changes or whatever.
I'm sorry but, no.
Most of us can at least tell that Obito himself is a psychopath of sorts. If he wants to blend in, he will.
Back in the day when Obito (Using his Tobi alias) was a dumb guy with a Sharingan... Well... He was blending in. He was manipulating Akatsuki from within without anyone knowing so. He blended in by acting really stupid and when things got serious he would become "Obito" rather than "Goofy Tobi".
In the end, though, Obito has always been Obito. Even if it is revealed that Tobi is a different character, most of us can establish that Obito "wore" Tobi at some point in his life and simply used the name "Tobi" to do what he did without anyone knowing he was really Obito.