Just a thought, we now know that Madara awakened his Rinnegan before he died in the past, what if he ended using the “Creation of All Things” jutsu which the Rikudou Sennin used to separate the Juubi, to create Tobi?
Based on himself, Madara created a “clone” of sorts with all of his memories or most of them (would explain why Tobi has such an intimate understanding of Uchiha Madara)? And if Madara knew about the fuuinjutsu (sealing techniques) of the Uzumaki Clan and those of Uzushiogakure (Hidden Eddy Village), it would explain why Tobi knew about the time when the seal on Kushina would weaken. Since Madara awakened his Rinnegan and had both Senju (Hashirama’s DNA) and Uchiha blood, it is possible that he could use abilities the Rikudou Sennin could to an extent. Madara may not have performed the jutsu properly or have the required chakra/skills to perform it properly and consequently created “Tobi” in an “incomplete” form, explaining why Tobi’s face looked so sickly from the times we’ve seen it. If Zetsu was there at the time, he could have used his abilities to help Tobi’s “incomplete” body, or Tobi could have created Zetsu with Hashirama’s DNA that was in Madara’s corpse to help him “fix” his body. The reason for Madara creating Tobi could be for him to find a way to revive Madara if he was dying and/or not waste away his prime by waiting for opportunities to capture the Tailed Beasts which could take decades; he could have created Tobi to act as him and capture the Tailed Beasts before reviving him in his prime with the Gedou: Rinne Tensei no Jutsu (Outer Path: Samsara of Heavenly Life Technique) – the jutsu Nagato used to revive the Konoha shinobi. But Tobi, living a life of superficial existence based on someone else and lacking the primary attribute which causes a “person” to feel “alive”, their “identity”, Tobi could have diverged off onto a path of his own choosing ie. The Eye of the Moon Plan rather than the plan Madara has in mind – have himself become the Juubi’s Jinchuuriki.
The fact that the “Creation of All Things” jutsu utilises spiritual energy and it’s yin and yang components to create shape of form from nothingness and breathe life into it, could be the reason for why Tobi refers to himself as “no one”.
And as for why Madara trusted Tobi with his plan, well effectively it’s because Madara was trusting himself and whom better to trust then yourself? Madara just unestimated the power of “individuality”.
Tobi being shocked when Kabuto brought out the sixth coffin containing Madara has always had me intrigued, just why did Tobi react in such a way? It is possible that seeing Madara reminded Tobi of his actual mission, hence the shock. Just to play it safe and keep his “enemies” close he accepted Kabuto’s offer. It could also be possible that he accepted Kabuto’s offer because he didn’t want Kabuto to learn what exactly he intended to do.
Did Tobi acquire the Rinnegan from Madara’s corpse?
I still don’t entirely get how Tobi is the one who spurred Yahiko to form Akatsuki and was the one who gave Nagato his Rinnegan =/. Madara appears to know Nagato is some manner, so it is possible that Madara put his plan in motion then, and before he died prepared Nagato for his Rinnegan eyes. Tobi’s job was to keep Nagato under control and use him to resurrect Madara, but Naruto totally screwed that plan up when his enlightened self had a changing effect on Nagato and Konan. Madara must have known Nagato was an Uzumaki beforehand, but I still don’t get how exactly Nagato was “given” the Rinnegan.
The uniqueness of Tobi’s right eye really is a mystery in itself, I don’t think it’s part of Madara’s plan but something Tobi acquired during his time “alive” – yes I believe that right eye of his is the Sharingan he acquired from Obito’s body.
The fact that Madara doesn’t call Tobi by his name indicates the potential that Tobi didn’t take on that name when he was with Madara (if “Tobi” and Madara are acquainted). If Tobi really does have Obito’s Sharingan, did he take on a name similar to Obito after meeting him? And was Obito the reason for Tobi diverging from his mission to revive Madara and seal all the tailed beasts inside the Gedou Mazou (potentially Obito could still have been alive when Tobi met him – he wasn’t shown to have died when the cave collapsed)? Did Obito’s final wishes and desires spark something inside Tobi and cause him to wonder what he wants and realise that wanting something and individuality is what leads to suffering and inevitably to war and thus to bring true peace, “individuality” must cease to exist. Nagato used to believe that just by living, people will hurt each other and as long as people live, hatred will exist, only until Naruto reminded Nagato of “another path” did Nagato really believe change was possible. Looking at things now, Tobi and Nagato’s goal really were similar.
So if the Gedou Mazou is destroyed, both Tobi and Madara’s plan goes up in flames…I wonder if Tobi’s plan will fail because Madara will intervene with the intent of actually feeding the whole chakra of the Hachibi and Kyuubi to the Gedou Mazou in order to revive the Juubi completely. And if the “incomplete” Juubi is already revived, will Madara stop Tobi from carrying out “The Eye of the Moon” plan and instead become the Jinchuuriki of the Juubi himself. Madara is the type who overestimates himself and holds his power back due to looking down on people (he doesn’t think an “adult” should fight seriously against a “child”). Will the fact that he has an immortal body now (which he believes is a fortunate twist) come back to bite him? Madara is a prideful and in some ways arrogant person, so he may very well believe that this new “enhanced body” he has will be sufficient to act as the host of the [incomplete] Juubi, which may be proven false when the [incomplete] Juubi unleashes, rages and reigns destruction over the world. This could very well provide the next antagonist for Naruto and Co. (and Sasuke) which would explain why Kishimoto-sensei still intends for Naruto to run for at least a year and a half.
Also Tobi required Sasuke for the Gedou: Rinne Tensei no Jutsu (Outer Path: Samsara of Heavenly Life Technique), but with him implementing “The Eye of the Moon” plan, does he even require Sasuke anymore? Sasuke was required to fill the role Nagato was supposed to play (revive Madara), but with Tobi seemingly lacking the intent to revive Madara, who has already been revived in a way, is Sasuke no more needed by them?