ok guy's I'm new around here so I don't know if someone already though about this, but anyway, please leave your thoughs
So I went almost over all Tobi theories around the forum and found some really interesting the most convincing is Tobi=Kagami.
We know that this guy was in Tobirama's team, with Hiruzen, Danzo, the 2 other elders and the Akimichi guy, we saw all of them later when the Kyubi attacked Konoha, we also saw that Danzo and the Uchiha were missing, we don't know if Kagami is already dead or if he(Tobi) worked along with Danzo and the Uchiha in oreder to attack Konoha.
I'm convinced that Madara, Kagami and Obito are all related. As we know Hiruzen was the student of the first and the second hokage, so I think that Kagami may be possibly Madara's son and not some kind of clone, hatred clone, genjutsu or Sasuke from the future crap. I beleive that Kagami being Madara's son may explain how the 2 men know each other and seems to work together, he carry the hatred of his father, he helped to murder the clan that betrayed his father, he claimed to be had his father's powers in sing of repect, he also said that he admired Hashirama and hated him beacause he defeated Madara, so the guy definitely knows Hashirama and Kagami was definitely around in Hashirama's era.
Maybe Kagami used the DNA of the zetsu to make his life longer which explains the use of izanagi and the white fluid. By being madara's son he may also took the Rinnegan when Madara died, then he put it in Nagato.
Then my theory of Obito being Kagami son! Asuma is about the same age as Kakashi and Kakashi the same age of Obito, so if Asuma was the son of Hiruzen maybe Obito is the son of Kagami, it perfectly make sense. So when obito was crushed by the boulder he took obito's eye and that may explain his space-time ninjutsu that looks a lot like Kakashi.
This may also explain why he said to Kakashi "I'll deal with you latter" he maybe what to take revenge on his son.
:shrug:
That pretty much it, if I missing something please tell me nd if I'm wrong please say it, leave comments.