With the unfolding of the main events in Attack on Titan, the character of Zeke Yeager eventually emerged as a strong deuteragonist. And in Episode 74 (“Sole Salvation”), fans are treated with the origin story of this inheritor of the Beast Titan.
It was there that Attack on Titan fans witness the parental neglect that marked his entire childhood. As a result of which the timid, unsure little Zeke sought refuge in the assuring and comforting presence of Tom Ksaver.
[Note: The article reflects the writer's own views and contains spoilers of Attack on Titan up to Episode 74]
How Tom Ksaver and Zeke's bond flourished to such heights in Attack on Titan
Meeting Tom Ksaver
Forced to join the Marleyan warrior unit by his parents, Zeke struggled to keep up in the army. As an Eldian soldier himself and recognizing the futility of this Marleyan regime, Ksaver took the overwhelmed, anxious little boy under his wing.
Meanwhile, the constant pressure and brainwashing that the young boy was subjected to at the hands of his own father Grisha Yeager, suffocated and traumatised him to a great extent.
In the middle of enduring rigorous physical training of a warrior and facing emotional turmoil at home, the only sanctuary for the young kid was the company and understanding that he received from Tom Ksaver’s end.
Taking Ksaver's advice
A frantic and terrified Zeke, was afraid of his family getting caught for plotting a coup against the Marleyan Government, and came to Ksaver.
After listening to the Restorationist ways of Grisha Yeager and Dina Fritz, the older man convinced the young boy that he should turn in his parents to the Marleyan authorities, so that he could at least save himself and his grandparents.
Consequently, acting on Ksaver's advice would go on to not only ignite a chain reaction in Zeke's life, it would also shape his ideology, as seen later in the story.
Ksaver's influence on Zeke's ideology in Attack on Titan
Be it his own parents' Restorationist ideology or his grandparents feeding him the Marleyan narrative regarding the Eldians, Zeke as a young boy had always found himself to be imposed upon by others and their respective set of beliefs.
Naturally, once out of their control, he learned to think on his own. However, his close proximity and emotional connection with Ksaver had colored his belief system and thought process without him even realizing it.
Zeke's plan to euthanize the Subjects of Ymir (Eldians) was markedly incited by his interactions with Ksaver, especially in Episode 74. Fans saw the titan researcher revealing his new findings as to how the bodies of Ymir's subjects could be redesigned with the power of the Founding Titan.
This prompted an easily impressionable adolescent Zeke to vouch for an end to all sufferings by stopping the procreation of the Eldians. Moreover, Ksaver's pitiful admittance of “If only I hadn't been born in this world!,” further strengthened his protégé’s conviction in his nihilistic ideology.
Tom Ksaver, the father figure to Zeke in Attack on Titan
Starved of all sorts of parental affection at home, little Zeke eventually turned to look for it in the person of Tom Ksaver. On the other hand, having lost his own family, this predecessor of the Beast Titan sought the image of his lost son, in Zeke. This led their relationship of mentor and student blossoming into that of father and son in Attack on Titan.
In fact, a rather mundane activity like playing catch with his father-like mentor, became an integral part of Zeke's life. This is continuosly showcased as fans see him incorporating the same moves in battlefield, where he throws projectiles in the manner of pitching. His deep attachment to Ksaver can also be noted in his holding onto the man's glasses as a keepsake.
Towards the end of Attack on Titan's Episode 74, a captive Zeke is seen remembering his memories and time spend with Ksaver. The bespectacled researcher had impacted his life so much that at one of his most vulnerable moments, he calls out to the former.
Afterwards, when a vindictive Levi mercilessly cuts off the bearded man's limbs, the latter goes for what can be deemed only as a suicidal act when he detonates the thunder spear attached to his stomach, while shrieking out: “Ksaver-san, please watch over me!”
In the end, Tom Ksaver was to Zeke what Grisha Yeager could never become – a father who cared for him and showed him love.