Aaroniero Arruruerie

In place of an ordinary head, Aaroniero carries a tall glass cylinder brimming with crimson fluid, and within it drift two tiny Hollow faces, each branded with the number nine. The upper one rumbles in a low voice while its companion pipes in a shrill, childlike tone, and the pair behave almost as separate minds. Long weary of the stares and muttered comments his real head provokes, he keeps it hidden beneath an elongated white mask riddled with eight holes whenever he stands in light or moves among his fellow Espada.

His attire also breaks from the standard Arrancar look, trading the usual jacket and hakama for a full body robe worn under a frilled nobleman's coat and finished with a single gentleman's glove. Fragments of his shattered Hollow mask still cling to both faces, three quarters covering the top head and half the lower, while the hole that marks his Hollow origin rests on his left thigh.

Aaroniero takes clear pride in his capacity for ceaseless growth and in the rank he occupies, a height no other lowly Gillian has reached. A streak of cruelty defines him, for he delights in tormenting opponents, especially when his absorbed memories hand him secrets to exploit, and he leans on Rukia Kuchiki's guilt over Kaien Shiba by pressing her to cut down her own allies. His two faces carry separate temperaments and often trade lines as though two speakers share one body, referring to themselves in the plural whenever they are laid bare. At the moment of death the lower face shrieks and begs Aizen for aid while the upper spits a last curse, yet in his borrowed guise he never once speaks of himself as more than one.

Before his ascension, Aaroniero was a mere Gillian, the feeblest tier of Menos, and he would become the final survivor among the first generation of Espada. His path to power ran through consumption: by swallowing Metastacia, the Hollow that had slain and merged with the Shinigami lieutenant Kaien Shiba, he claimed both that creature's fusion ability and Kaien's own techniques, memories, and Zanpakutō.

He appears only briefly during Aizen's creation of Wonderweiss Margela, watching from shadow with his mask off, then dons it to join the assembled Espada when intruders breach Hueco Mundo to reclaim Orihime Inoue. His true test comes when Rukia Kuchiki reaches the darkened tower he calls home. Claiming he cannot bear sunlight, he lifts his mask to reveal the face of her dead mentor, then spins a tale of how Kaien's body was rebuilt in Hueco Mundo with himself at the helm, all so he might one day avenge himself on Aizen. The story is a lure. He begs her to atone by killing her friends, and when she refuses and draws Sode no Shirayuki, he answers with Kaien's water spear Nejibana and overwhelms her.

Rukia eventually notices him shrinking from the light, pins him with Kidō, and tears open a wall so the sun exposes his real form, the twin heads floating in their tank. He then lays his secret bare: he is the sole Gillian among the Espada because his Zanpakutō Glotonería lets him consume dead Hollows without limit, tens of thousands of them, Metastacia included, letting him wear Kaien's spirit body and mimic him perfectly. He impales her on Nejibana, certain of victory, but the still conscious Rukia grips the blade and unleashes San no mai, Shirafune, driving it through his capsule. The lower head dies screaming that Aizen swore it would never again feel pain, and the upper curses one final time before the glass splits apart.