Originally posted by: DarthEnder
I don't hold with Mutata's belief that the red eyes was simple forshadowing. If it was, he wouldn't have made mention of how he was in danger of losing control.

Of course, I don't believe he has a cursed seal either.

Actually, if you look at the evidence logically, the most reasonable belief to have is that Kabuto has an animal demon in him just like Naruto.

After all, he regenerates just like Naruto. And it's something inside him that has to be held in check to keep it from getting out of control.

Though, I also don't think that's the case either. It's simply what the evidence points too.

After all, if he had that, like Mutata said, why didn't he use it in the Sannin battle. Unless even Orochimaru doesn't know about it and Kabuto wanted to keep it that way.
Of course this is a good point, unless in the manga they had kabuto say that he was in danger of losing control, then they would have put it in because that's the black and white way of foreshadowing. The red eyes were just added in by the anime they should not be a point of discussion for Kabuto's future power.