I think tobi is a clone of madara with zetsu cells with madaras memory. It's possible i mean if they could make zetsu who isnt really a person but has a personality madara might have made a clone of himself with hashiramas powers to carry on his plans and bring up nagato in akatsuki and then get nagato to revive the real madara. Obviously thing didnt go to plan because when madara was rezzed he thought it was nagato first but then was told it was edo tensei as nagato had a change of mind and helped naruto and died. Tboi also said im a shell of my former self which compliments the clone theory and he also said i am no one which also compliments the clone theory s he isnt really anyone as he's ( in this scenario ) a clone. We wont really know until kishi really tells us but it sounds plausible to me 
Please point out any flaws and maybe give your own sensible theories:izuna:
Please point out any flaws and maybe give your own sensible theories
:izuna:
