A Transmigrator's Story in the Hyuga's Main Branch

Since long ago, Black Zetsu harbored a deep-seated fear and covetousness for the Giant Tenseigan on the Moon, a formidable weapon developed by Hamura and his descendants.

After Hamura's death, Black Zetsu finally seized the chance to plot against them, once upon a time, many centuries ago, only to confront the harsh reality of their power—Hamura's eyes had been transformed into the Giant Tenseigan, designed as a safeguard for future threats.

This harsh lesson shifted Black Zetsu's focus towards manipulating events on Earth firstly, particularly among Hagoromo's descendants: the Senju, Uchiha, and notably Madara, with DNA from both of those great clans, whose endeavors with the Rinnegan became central to all of his schemes.

The daunting power of the Moon's Otsutsuki clan deterred him from initial confrontation temporarily initially; instead, he aimed to resurrect Kaguya using the earthly remnants of her powers and genes,

Including Madara's future resurrected powerful body with both complete Rinnegan and Senju Hashirama's cells and all the chakra from this planet collected using the Infinite Tsukuyomi jutsu he successfully brainwashed and filled Madara's brain with so far; it would be enough to bring back a pretty powerful version of his mother right away. 

Black Zetsu's ultimate plan was thus very intricate: first, revive Kaguya on Earth and then harness her sufficient partial power to ascend to the Moon, where she could fight off and merge with the Giant Tenseigan and reclaim all her original chakra, restoring her full might.

He understood that Hamura's lunar descendants were tasked with guarding the Gedo Mazo statue, which was the Ten-Tails' remaining husk after its chakra had been taken away and sealed inside Hagoromon—both concepts were key components of this entire grand design.

Fortunately, the Madara's Rinnegan's ability to summon the Gedo Mazo and successfully break the seal created by them for the husk on the Moon, a later possibility unbeknownst to Kaguya's twin sons, meant that Black Zetsu didn't need to confront the Moon's Otsutsuki directly in order to kickstart his partial Kaguya revival plan at first and face them way easier in that way through Madara with both the Rinnegan and the Gedo Mazo if need be for that.

Yet, actually testing this through Madara directly, Black Zetsu was relieved to find that the Moon's Otsutsuki never even attempted to retrieve the Gedo Mazo after he first took it many decades ago and has kept it here on Earth through Madara as a proxy ever since.

This suggested that fortunately for him, they were either unable to travel to Earth or had significantly weakened over the centuries.

This realization bolstered Black Zetsu's confidence in his plans, easing his concerns about a potential fierce counterstrike from the Moon descendants.

However, the unexpected emergence of formidable powers within the Hyuga clan—Hamura's other descendants on Earth—reintroduced an old fear. This new development forced Black Zetsu to reassess the potential threats from Hamura's lineage and tone down his arrogance. 

However, amidst the tense discussions and strategic recalibrations, White Zetsu injected a lighter note into the atmosphere with his characteristic playfulness. In a joking tone, he remarked, "It seems like today, the Uchiha clan is more likely to follow and be subordinate to the Hyuga, for some reason, rather than the other way around.",

"I mean, even if they were forced to get allied, it's clear who has the upper hand nowadays and leads over the other. So, how does that sit with you, Lord Madara?", White Zetsu's eyes turned a bit teasing. He was inherently spirited, so he often seized opportunities to tease even someone like his boss.

Madara responded with a dismissive snort immediately, his voice tinged with arrogance, "Huh, if they had listened to me back then, they wouldn't be in this predicament now. I warned them exactly how the village leadership would turn against them and treat them eventually, and look what happened.",

"But since they chose to abandon me and draw their own line in the sand idealistically, then I couldn't care less about what happens to that clan now...", His tone was cool and detached, a true reflection of his feelings towards his birth clan, which had once been central to his plans but had since lost his favor and made him hate it.

"However...", Madara continued, his interest piqued as he considered the latest developments within the Uchiha, "Notably, this new generation has seen the awakening of two Mangekyo Sharingan at the same time.",

"Even during the Warring States period, such occurrences were exceedingly rare...", His eyes narrowed thoughtfully, analyzing the implications, "It's a pity, though, that both holders are from the clan's leadership lineages. True aristocrats of the clan, deeply entrenched in its heritage and unlikely to turn against it."

Madara's expression hardened slightly as he weighed his options, "If circumstances were different, I might have attempted to recruit them, much like I did with Obito. Their power and potential could have been invaluable to our plans.",

He paused, a sly smile crossing his old face as he concluded, "But at least Obito is with us, shaped by our ideals and completely loyal to our cause."

As Madara's thoughts lingered on the potential of the Uchiha and the reality of Obito's allegiance, White Zetsu suddenly chimed in again with a sly grin, picking up on the thread of the conversation,

"Speaking of Obito, he's just about to wake up...", White Zetsu announced, the timing almost too perfect, lending a playful twist to the discussion.

"Seems like we always have at least one Uchiha on our side when we need it, right?", White Zetsu teased, lightening the mood with a touch of humor that played on Madara's complex history with his clan.

"Then we should wrap up this discussion before Tobi brings him here...", Madara said, shifting his focus back to the present matters.

"The crucial time has come. Obito's initial training is complete, and soon Nagato will find himself facing a significant challenge. It will be the perfect opportunity for Obito to step in and lend a 'helping hand,' ensuring Nagato's alignment with our cause from then on. This intervention will be critical in bringing Nagato fully onto our side."

Madara's gaze hardened as he outlined the next steps, "You three need to make your way there immediately to ensure everything happens precisely as planned.",

"This mission will be Obito's first real test, a chance for him to prove his loyalty and usefulness to me. It's a pity I won't be alive to see it unfold directly.",

"That's why I must rely on you to guide Obito until I can be revived through Nagato's actions a few years later...", he instructed, laying out a clear and strategic path forward.

His voice carried the weight of inevitability, and the deep machinations of his long-term planning underscored the critical roles each played in orchestrating his vision.

Over the years, Madara meticulously crafted his vision for peace through what he termed the Eye of the Moon Plan.

However, as his life neared its end, he realized that he wouldn't live long enough to see his plans come to fruition.

Madara devised a contingency, utilizing the Rinnegan eyes he had awakened from integrating Hashirama's Senju cells into his own body through the wounds he had sustained.

He covertly transplanted these powerful eyes into a young Nagato, all without the boy's knowledge, hoping that Nagato would one day use them to resurrect him using one of its most otherworldly techniques called the Rinne-Rebirth, albeit at the expense of his life.

Understanding that this plan required careful manipulation and guidance, Madara knew he needed a reliable agent to steer Nagato towards this destined path.

But that agent also needed to be very powerful to control someone equipped with Rinnegan, which is way more powerful than two Zetsus, for example.

While sustaining his life through a connection with the Demonic Statue, Madara vigilantly observed Konoha, and he has been searching ever since for the perfect candidate to fulfill this role.

Ultimately, his patience paid off when he identified Obito as the ideal pawn to advance his ambitions, setting the stage for the next phase of his grand scheme.

He not only had great potential but was also quite vulnerable and exploitable to be of use!