[Discussion] Why did sasuke join the side of Tobi?

[BLAZE]

u will know if u read the manga bruh
Obito said the kyuubi attack was natural disaster and he has no hands in it.Also Sasuke was nvr completely on obito's side.He was using him for his owm goals

Another good question is why Tobi lured Sasuke to his side, the answer is simple, when Itachi died Sasuke had lost relevancy, so in order to make him relevant again, he had him join up with Tobi to make him antagonistic to Naruto again.

But thats what plot is
its like telling the same that obito or many others were introduced in relevence to keep plot going or to keep parallels relevent

 

[Uchiha Samater]

Sasuke became warped that's why

Remember despite internally acknowledging that the ''masked man'' was speaking the truth to an extent, and thus decided to cooperate while he was there.

Despite this,

He still felt it necessary to question those responsible in order to fully believe it.

For example look at his response when he questioned danzo, and from there his hatred ''matured'' against the leaf:

1.

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2.

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3.

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Karin even noted multiple times in that arc how his chakra was changing


Add this to Tobirama's explanation regarding the Uchiha and the hatred, you see a a valid explanation into sasuke's actions

 

[BLAZE]

To the overall cohesion of the plot it wouldn't matter if Sasuke's character disappeared with Itachi, much like how irrelevant it was for Tobi to recruit Sasuke to join his side, it's extraneous shoe-horning just to make a character relevant again to appease a certain group of the author's readers.

Not really
That's what sasuke's char is.It's darkness.
He is not Naruto he is his opposite.He is the scenario that naruto may have ended in just like obito;Nagato etc.
As said he can be dyed any color but the fact is his decision r his own.The thing matters is how much influence u have over.
It fits perfectly as Itachi has most influence ovee him and obito played his gamble by putting Itachi as a victim who lived more horrible life than sasuke.As hatred for Itachi and his own life living as LAST of his clan the gamble easily worked.