This chapter was co-written by JeffC FTW
Enwrapped within his cocoon, Lord Orochimaru had achieved everything he could ever want. He was the most perfect being in the world. Every jutsu in the world he acquired, and not only did he use it for himself, but he found peace in the form of only a few people he accepted more than anyone or anything else: Jiraiya and Tsunade, even dear Sasuke and his friends. He defeated death and had no fear of it. He even found a far better jutsu to live forever than the immortality technique where he had no more need to steal someone else's body...except hundreds upon hundreds of years later.
He was free to come and go in the Leaf Village, performing wonders with his research and granting his abilities to others who wanted to live forever and study the wonders, applying them to the needs of others. It was a perfect world.
Sasuke became Hokage when his time came, appointed him his right hand man after everything Orochimaru gave him in his revenge against Itachi and those who wronged his elder brother. Even those enemies who backed his beloved brother into the wall were crushed, as were others who dared to oppose their home and their shared comrades. In the end, everyone was happy. There was no need to compromise or sacrifice.
In the real world, Orochimaru had reached his limit. Satisfied and sated after gaining his deepest desires, it was time for what was as close to perfection as he could get. He mumbled, chuckled and smiled all in one, unaware of what was really happening to those around him, and would happen very soon to him as well.
Orochimaru's clothing was gone. His lean, pale body was nude even revealing a sexless section as he was really no longer either man or woman, nor was he completely serpentine as he waited for the next body. Within was the snake he became, also acquiring the White Zetsu cells along with his myriad of jutsu: his own and those he stole from others. But he would no longer need those, mused Princess Kaguya.
She scolded him, telling him how vain and ruthless he was. How he was never satisfied with what he already had, but now he would have no choice in this matter. She promised him that she would give him what he truly desired, which was perfection without worry. All chakra would be hers, and so she harvested all of his and those he took. No longer would he be the Legendary Snake Sannin, but an obedient soldier of the Moon Princess. She told him he would follow her orders and never abandon her even if it ever crossed what would become his new mind, nor would he be fascinated with anything other than her orders and the incoming trespassers.
Orochimaru's jutsu gone, his body and intelligence followed suit. His flesh and muscle mass shrunk over his bones, his serpentine features shriveling like a mummy, and leaving behind the withered husk of a snakeskin. Only he wouldn't leave this body for another; he would regain but also reform. The thrills were exciting in itself. Almost more than anything he could have recalled - those memories now erased along with his name. Snake mutant would be no more, but a plant form close as human as possible.
The result became just that. The body began to liven up in thanks to the tree's nourishing source: the skin remained white, shrivel becoming ripe again, though cracks replaced any scales, and the shoulders and chest became broader than before. Long black hair shortened and turned into earthly green, his golden yellow eyes darkening a shade, and the purple marks framing his irises vanished, as well as his snake-like features. Just as his past life, he appeared male but had no real gender in particular.
The cocoon snapped from the Shinju Tree, just like the million others.
White Zetsu took the place of Orochimaru. Another past Zetsu taken over but now brought to the surface. No more worries about dying, except for the matron and progenitor of all chakra which would never be his. He joined the ranks which were once Kabuto, Karin, Jugo and Suigetsu who didn't recollect themselves or even him. That was perfectly all right with him. He looked forward to protecting the mother goddess who completed uniting all chakra into the new fruit which was rightfully hers.