Chapter 46:
According to Orochimaru's research, the reason the Uchiha clan is prone to being warlike and arrogant lies within their genetic structure. Their genes contain a special power that is triggered by heightened emotional state and spiritual energy. This stimulation manifests as their famed Sharingan, which is essentially a physical representation of their immense spiritual power.
However, there's a catch. The mental energy tied to the Sharingan is so vast and powerful that even modern Uchiha bodies struggle to contain it. Any significant emotional or external stimulation can easily cause mental instability. The extent of this instability varies, ranging from becoming excessively combative and prideful at best, to outright madness at worst.
Because their bodies aren't strong enough to suppress the overwhelming spiritual power of the Sharingan, many Uchiha end up acting irrationally. This could explain why Tobirama Senju, the Second Hokage, once called the Uchiha the "clan of evil."
Still, Orochimaru, with his knowledge of the plot, understands that the Sharingan isn't inherently evil. The source of its power traces back to something much older and more complex the chakra fruit of the God Tree.
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According to legend, the God Tree is the Ten-Tails, a monstrous entity that serves as the source of all chakra. Kaguya Ōtsutsuki, the progenitor of chakra, consumed the chakra fruit of the God Tree, which caused a drastic shift in her personality and granted her overwhelming power. The chakra fruit's energy merged with her body, and these abilities were passed down to her descendants.
Orochimaru's analysis and knowledge of the show deduced that Kaguya's power is divided into three distinct aspects. Her own power: The Byakugan, an ocular jutsu passed primarily to the Hyuga clan. The God Tree's power: The Sage's body, representing physical energy and durability. And finally, the Chakra Fruit's power: the Nine-Tomoe Rinne Sharingan, which represents spiritual energy and advanced ocular jutsu, like the Sharingan and Rinnegan.
Initially, these three powers were unified in Kaguya. But as her bloodline spread through generations, the powers split, becoming less concentrated.
Orochimaru focused primarily on the powers of the God Tree and the chakra fruit. If the God Tree represents the root of chakra and physical energy, then the chakra fruit is the source of immense spiritual power the force behind the Sharingan and Rinnegan.