Zeke Yeager, known as Sieg Jaeger, is the royal-blooded Eldian half-brother of Eren Yeager, born to Grisha Yeager and Dina Fritz within Marley’s Liberio internment zone. Shaped by his Restorationist father’s radicalism and a mother bound by royal lineage, he endured childhood neglect when conscripted into Marley’s Warrior Program as a spy. Propaganda and tales of Eldian atrocities from his Marleyan grandfather cemented his belief in Eldia’s inherent curse, driving him to betray his parents to authorities—an act that condemned them to Titanization on Paradis Island.

Mentored by Tom Ksaver, inheritor of the Beast Titan, Zeke embraced nihilism, advocating Eldian extinction via sterilization as moral absolution. Assuming the Beast Titan at seventeen, he ascended as Marley’s deadliest Warrior, wielding strategic brilliance and a primate-like Titan form with furred limbs, dark sclera, and lethal projectile precision. His spinal-fluid injections granted command over Pure Titans, instrumental in victories like Fort Slava’s siege. Yet he harbored paradoxical empathy, mourning Paradis civilians as casualties of a “necessary” purge.

A tactician of icy pragmatism, Zeke enforced mission-first discipline, discarding allies like Annie Leonhart and coercing Reiner Braun to prioritize retrieving the Founding Titan. Though he masked vulnerability beneath detachment, flickers of rage or pity surfaced when confronting Eldian exploitation. Posing as Marley’s loyal weapon, he secretly manipulated both nations to advance his sterilization scheme, briefly allying with Eren under false pretenses of unity. Their pact shattered upon uncovering Eren’s memory tampering with Grisha and his intent to unleash the Rumbling.

Zeke’s endgame hinged on royal-blood contact with Eren to activate the Founding Titan. Captured by Levi Ackerman, he engineered an escape via Titan transformations before reuniting with Eren in the Paths realm. There, he implored Ymir Fritz to enact sterilization, only for Eren to usurp her allegiance for global annihilation. Confronted by Grisha’s memories of paternal love and his own yearning for belonging, Zeke allied with Levi to cripple the Rumbling. His final sacrifice in severing the Titan curse facilitated Eren’s downfall.

Zeke’s trajectory—from traumatized heir to disillusioned revolutionary to resigned redeemer—echoes the corrosive legacy of inherited guilt, the allure of extremist ideology, and the fragile duality of destruction and deliverance within war’s eternal cycle.