Re: Tobis Identity 100 percent spoiler
I have a waaaay out there hypothesis for who Tobi is.
Now, bear with me, it will make (somewhat) more sense as you go down further.
Tobi is Sasuke.
Now, hear ME out: Lets imagine a past where Tobi mascarading as Madara never existed. Danzo enlisted Itachi to kill off the Uchiha. Without Tobi, Itachi does, but is fatally wounded. He still spares Sasuke, but Itachi is branded a traitor and the entire bloodline "cursed" in the eyes of the village. Sasuke grows up a pariah, as he is shunned by everyone. He probably resorts to childish pranks to get attention.
Enter Naruto. Without Tobi to summon the 9 tails, the 4th and Naruto's mother survive the pregnancy. Naruto, the son of the Yellow flash, grows up as an elite, beloved by the entire village. He probably becomes the love interest of Sakura, while prankish Sasuke is the nuisance. (Notice that Tobi early on was a prankster too)
Being the best and the worst of the class, they end up together in the same team. Naruto gets hurt against haku protecting Sasuke, and since the Kyuubi is still in his mother, he doesn't have the kyuubi chakra to help him out, Sasuke's sharingan awakens, and he somehow saves the day.
The deviations start to become apparent because Naruto probably dies against Gaara, which probably awakens the Mangekyo. Sasuke, losing possibly his only friend, goes willingly with Orochimaru and Kabuto, since Orochimaru wanted the Sharingan to begin with in both timelines.
Sasuke still beats Orochimaru, and with the mangekyo sharingan actually defeats him completely. Pressuring Kabuto, he finds the reconstructed dead soul body of Uchiha Madara, and takes his eyes, unknowingly taking the malignant wood type cells of the 1st hokage as well. He learns of the hidden room, and with Madara's eyes he also has a bit of Madara's chakra, so he can summon and control the 9 tails.
I imagine that Danzou's spies have alerted him to Sasuke's plan to destroy the leaf and come for Danzou, and Danzou wants his eyes anyway. My hypothesis is that Danzou beats the absolute hell out of that Sasuke, who resorts to the OTHER forbidden technique of the sharingan, Izanami. Izanagi undoes the effects of the present, so I'm going to go out on a limb and say that Izanami undoes the past. It hurtled Tobi into the past, probably a few decades.
Note that Izanami was used with just a normal sharingan. We have no idea what it's abilities are if used in mangekyo mode are.
I'm going to assume that Tobi wanted to raise an army against the leaf, initially, so he defected into the land of the hidden mist, even becoming the 4th Suikage. Or even just controlling him. If that is the case, then it would explain where he learned about the vast power of the tailed beasts.
However, being the kage of the country that sees countless war, Tobi lost the desire for revenge. He was weary of seeing people die, and he just wanted it to end.
Having lost one of his eyes due to the use of the Izanami, the nature of the sharingan changes where it affects space-time interactions in the present. Like Kakashi's eye.
He could have acquired another sharingan anywhere, though most likely was when he helped Itachi slaughter the Uchiha.
And then, after reading the information under the tatami mat, and learned about the ability to use the moon to induce permanent genjutsu. He, from his long life, is weary and not above using peoples emotions against them to just end it all.
He learns that the host of the 9 tails, the most powerful bijuu, is Naruto's mother, and she is giving birth soon. The act of stealing the Kyubi at that moment wasn't just because it was advantageous, he also wanted that elite a$$hole naruto to undrestand what true pain was, what it felt like to lose your entire family / clan, and be reviled by the entire village.
The rest is history.
THAT, is my hypothesis.
Ok, reasons why I believe this:
Tobi knew exactly how Sasuke would grow.
He showed up exactly when Itachi was about to slaughter the Uchiha. That is a heck of a coincidence.
The Kyubi telling Sasuke how much his eyes were like Madara's. As well as the Kyubi's cryptic message.
Tobi' strange fondness of Naruto at times seems nostalgic.
The way he knows things about Itachi that even surprise Itachi.
The fact that despite needing to collect the biju in order, he has Itachi and Kisame attack Naruto, knowing that Sasuke would intervene, fail, and then be more likely to follow Orochimaru, which he needed Sasuke to do to gain more power. And to eventually be rid of the curse seal.