yet another new theory about uchiha massacre
i thought of this last night after watching too many conspiracy theory shows and thought it was pretty plausible all things considered
what we know for a fact:
itachi was A spy in the uchiha for the elders
shisui died several days before shit happened
shisui has obscene hypnosis powers due to his sharingan that is almost impossible to detect
danzo has shisui's eye and apparantly his arm as well
itachi reported to all the third and all three elders, but trusted the third most of all
danzo is a minipulative bastard that is very radical
people distrusted the uchiha after the kyubi attacked, before the uchiha decided to plan the coup
Shisui was itachi's apparant best friend
what everyone ASSUMES:
itachi was the only spy
itachi killed shisui
danzo was only involved for the final order
shisui was secretly a spy for Danzo, and was silently instigating the coup to begin with because Danzo didn't trust the uchiha, and shisui was a member of root.
Danzo manipulated things so that not only was Shisui the best friend of the super genius Itachi, but that Shisui manipulated the clan to send itachi into ANBU and plan a coup in the first place to throw off the third and the other elders. After a certain point, itachi found out about Shisui, and shisui in turn found out about itachi knowing about him. That's when Danzo killed Shisui under orders and made it look like Itachi was involved. Then Danzo implanted shisui's eye and convinced the third and the elders for itachi to massacre his clan, assured that Itachi would keep quiet afterwards. Of course he didn't expect sasuke to still be alive and shit happened from there.
It can be tweaked a bit at the end there to be a bit more consistent, but i think that it in general makes alot of sense and explains alot in the storyline.