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.
Kaguya had two sons, Hamura and Hagoromo (the Sage of Six Paths). Each inherited a portion of her power. Hamura received Kaguya's Byakugan, which was passed down to the Hyuga clan. Hagoromo inherited both the Sage's body and ocular powers, which he passed on to his sons, Asura and Indra.
From this point, their powers began to diverge. Asura inherited Hagoromo's physical energy, granting him a strong body and vast chakra reserves. His descendants became the Senju clan. Indra, on the other hand, inherited the eye power, passing down the Sharingan to his descendants, the Uchiha clan.
This divergence in power created a fundamental difference between the two bloodlines. Asura's descendants, the Senju, were unaffected by the mental strain that accompanied the Sharingan. Their chakra and physical energy granted them strong, stable minds with a natural inclination toward kindness and cooperation.
Indra's descendants, however, inherited the immense mental power of the Sharingan. With it came a tendency toward extreme emotions. The greater their spiritual power, the greater their potential for instability. This explains why so many Uchiha become obsessed with power, often spiraling into madness when faced with loss or failure.
For example, Indra, Hagoromo's eldest son, became consumed by a lust for power, even going as far as killing his own kin. Madara Uchiha sought the Infinite Tsukuyomi after his younger brother's death. Obito Uchiha turned against the world after the death of his childhood love, Rin. Itachi Uchiha committed the massacre of his clan to prevent another war. And Sasuke Uchiha sought to destroy Konoha after learning of his brother's tragic fate.
In each case, the immense spiritual power of the Sharingan pushed them to extremes.
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All of this leads to one conclusion. Orochimaru realized that the Sharingan, as a power tied to the chakra fruit, is inherently unstable. The immense spiritual energy it generates requires a strong enough body to balance it.
Even the basic three-tomoe Sharingan has the potential to drastically affect its user's personality. For most Uchiha, their bodies simply aren't strong enough to handle the mental strain, which makes them prone to emotional volatility.
For Orochimaru, who has enhanced his own body using intermediate gene enhancement serums, the three-tomoe Sharingan is already the limit of what he can handle. Anything beyond that like the Mangekyō Sharingan would overwhelm him, causing his body to break down under the immense spiritual power.
In fact, after Hagoromo's era, the bloodlines of Asura and Indra diverged even more. The balance between their physical and spiritual energies weakened with each generation.
By the time their descendants evolved into the Senju and Uchiha clans, the divide was clear: The Senju retained the Sage's body, with its strong physical energy, but had little to no ocular power. The Uchiha, on the other hand, retained the ocular power, but many lacked the physical strength necessary to contain it.
Worse, as their bloodlines continued to dilute, fewer members of either clan could awaken the full potential of their powers. Many Uchiha, for instance, couldn't even awaken the basic Sharingan, and many Senju lost their renowned physical prowess.
What Orochimaru seeks to do is collect the genes of Uchiha members capable of awakening the Sharingan and use them to enhance his own eye power. Some of these individuals have already awakened the Sharingan, while others have not. However, the mere potential in their genes is enough for Orochimaru's purposes.
The more Sharingan genes Orochimaru collects, the stronger his ocular power will become after he fuses them with his own.
If Orochimaru gathers enough Sharingan genes, unlocking the Mangekyō Sharingan would be inevitable. Based on the Uchiha blood samples he's obtained from Konoha Hospital over the past two years, he already has enough to awaken the three-tomoe Sharingan, but the Mangekyō Sharingan remains out of reach.
Mainly due to one key issue: The Mangekyo Sharingan being too hard to awaken and many of the Uchiha who had awakened their Mangekyō Sharingan didn't leave blood samples behind in hospitals. Even if Orochimaru could access their genes, his current body isn't strong enough to handle the immense power of the Mangekyō Sharingan.
For now, Orochimaru will have to be patient, continuing his research until his body can withstand the next level of Sharingan power.