So let's say that Itachi snaps his fingers and seals
Hebi Sasuke into Naruto.
There are several different variables that would change the outcome of this event including but not limited to:
1:
Is Sasuke sealed within the same internal chamber as Kurama?
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Sasuke most likely completely suppresses Kurama with his Sharingan.
Let's not forget that a young an inexperienced Obito was able to control the Kyubii with relative ease during his attack on Konoha, and Hebi Sasuke should be of equivalent or superior skill with his Sharingan to that version of Obito.
Sasuke already shows that he’s more than capable of suppressing at least a portion of Kurama during his first encounter with Naruto in Shippuden.
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Kurama directly compares Sasuke’s Sharingan to the likes of Madara Uchiha, who was more than capable of suppressing all of the Bijuu
simultaneously. (not that I think Sasuke can do that yet, but its worth noting.)
This is a lot tougher because there are so many variables like I mentioned before. The answer to this changes depending on if Naruto is working with Sasuke or simply trying to contain him.
If he is
against Naruto, we can assume that Naruto would
Not make an active effort to free Sasuke as he does later with Kurama.
Instead, he would avoid internal interactions with Sasuke.
But John, Sasuke is Naruto’s closest friend. Why would Naruto avoid him entirely?
If we assume that Sasuke can leak chakra out of the seal, then we know that
Sasuke could Genjutsu Naruto during an internal interaction and take control of Naruto’s body permanently, similar to what he did against Orochimaru.
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(Hopefully, I don't need to explain why this would work).
On the other hand, If Sasuke is assisting Naruto, we would probably see something like this:
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We can assume that Naruto would take advantage of the Sharingan to boost his Taijutsu and Ninjutsu skills.
Maybe Genjutsualthough that is a bit unlikely.
2:
Is Sasuke cooperating with Naruto, or is he actively trying to escape like Kurama?
I already answered this above in the case of Sasuke NOT being contained in the same sealing unit as Kurama, so for this section, I’ll highlight
What would happen if Sasuke was sealed with Kurama, and was/wasn't cooperating with Naruto.
Naruto would be stupidly OP for a large portion of the series. Having both the powers of Sasuke’s Sharingan as well as KCM from the recently suppressed Kyubii, Naruto would be nigh unstoppable,
especially if he gains Sage Mode.
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(I couldn't find a suitable image of a Kyubii Sage Sharingan, so it would look like this but with the pupils signifying Kyubii influence)
I’d like to think that Naruto alone would be incapable of restraining both Sasuke and the Kyubii both actively trying to escape, but this is honestly up for interpretation.
One thing I do know is that
Naruto would be unable to rely on the Kyuubi to get him out of a pinch seeing as Sasuke has complete control of the Kyuubi.
This means Naruto has no access to either Kyubii V1/V2 or KCM.
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That's right boys, Naruto’s prime would effectively be Toad Sage Mode if this were the case.
3:
Is Sasuke capable of manipulating Naruto by leaking chakra from the seal-like Kurama can?
This variable really only matters if Sasuke is NOT cooperating with Naruto.
I already pointed out that Sasuke could Genjutsu Naruto if this were the case, but it wouldn't be too farfetched to believe that Sasuke could leak enough chakra to momentarily control Naruto just like Kurama does prior to befriending Naruto.
You've seen Kyubii rage mode, but have you seen
Uchiha rage mode?
We don't know exactly what this version of Naruto (Sasuke?) would be capable of, but one thing is for sure…
it wouldn't be pretty.
To put it in simple terms, nothing would happen unless Naruto was dumb enough to intentionally break the seal.
(It honestly wouldn’t surprise me if he did).
Sasuke would essentially just be trapped, waiting for Naruto to release the seal.
