Orochimaru

Everything about Orochimaru evokes a serpent. His skin is nearly white, his teeth taper into fangs, and his slit-pupiled golden eyes are ringed with purple markings above sharply cut cheekbones. Straight black hair reaches his waist, spilling around his face, and every body he later claims is reshaped to echo this original look, differing mainly in height. By the time of Naruto Gaiden his features have softened into something almost androgynous, the eye markings gone black, the hair gathered into a ponytail, the complexion paler still.

He usually wears loose beige robes over a black top, a heavy purple cord knotted at the small of his back, and blue tomoe earrings; during his Akatsuki days he donned the group's red-clouded robe with a ring on his left hand. His true body, remade by endless experimentation, is a colossal white serpent formed from countless smaller snakes.

Almost everyone who knows him, Tsunade included, lands on the same word for Orochimaru: twisted. Marked young by the loss of his parents, he came to loathe how fragile human life is and how deeply death wounds the living, and from that grew his craving to never die. His experiments on captive subjects were the means, a way to test the limits of the body and strip useful powers from others, all in pursuit of becoming an undying "ultimate being" who could take the many lifetimes needed to learn every jutsu in existence.

That ambition bred a god complex, a perfectionist's contempt for sloppy work, and genuine pleasure in frightening those he meets. His charisma binds followers to him, yet he spends them freely and betrays allies the instant it suits him, having murdered the Fourth Kazekage to wear his face and cast off Akatsuki once he failed to seize Itachi Uchiha's body. His deepest flaw is arrogance; certain of his own invincibility, he threw himself recklessly at Hiruzen and at Itachi and was left crippled both times. He took Sasuke Uchiha as a pupil meaning to claim the boy's body and Sharingan, an obsession that only curdled over time.

After Sasuke revives him, something shifts. Watching Kabuto Yakushi copy him wholesale teaches him the folly of imitation, and he chooses to fight beside the young Uchiha, mending Tsunade and the other Kage rather than ignoring the war. In his later years he pursues the secrets of life by gentler means, rebuilds his village, patches up his standing with Konoha's leadership, and sends his synthetic son Mitsuki there, hoping the boy will grow into his own choices.

Orochimaru grew up an orphan and trained under Hiruzen Sarutobi beside Jiraiya and Tsunade, standing out as a once-in-a-generation prodigy. A white snake he found near his parents' graves, said to represent rebirth, set him on a lifelong study of life's mysteries. After the three survived a clash with Hanzo during the Second Shinobi World War and were named the Sannin, he rose through Konoha's ranks and eventually served in the Root division under Danzo Shimura. There his research darkened into human experimentation: he implanted Hashirama Senju's cells into dozens of kidnapped children in a bid to recreate Wood Release, unaware that one, Yamato, survived.

He also learned the forbidden Impure World Reincarnation and, in time, perfected the Living Corpse Reincarnation, a body-swapping technique that let him transplant his soul into a new host every few years and so stretch his life indefinitely. His hunt for power carried him to the Ryuchi Cave, where he mastered senjutsu and, unable to enter Sage Mode, funneled that energy into his signature cursed seals. When Hiruzen finally caught him mid-experiment but could not bring himself to kill his student, Orochimaru escaped and drifted into Akatsuki, partnered with Sasori. His attempt to steal Itachi Uchiha's body cost him a hand and his place in the organisation, after which he founded his own hidden village, Otogakure.

During the Chunin Exams he branded Sasuke Uchiha with a cursed seal, and in the Konoha Crush that followed he reincarnated past Hokage to kill Hiruzen, though the Third sealed away his arms as he died. In battle Orochimaru wields the extending Sword of Kusanagi, commands serpents up to the enormous Manda, transforms into the eight-headed Eight Branches, and can call on every basic nature along with Yin and Yang. Slain by Sasuke in Part II, he was later rebuilt from Kabuto's flesh, undid the seal on his arms, and revived the first four Hokage to fight in the Fourth Shinobi World War. In the years after, he reforms into a wary ally of Konoha and raises his engineered son Mitsuki.