Why did Eren betray Zeke in Attack on Titan episode 78 and why did Zeke then trick his brother with the Founder Titan whilst in The Paths?

Attack on Titan has delivered not just another exceptional episode, but arguably one of the best anime episodes in history with episode 78 “Two Brothers”.

Whilst Falco and Colt, and Porco and Galliard had their own moments, it was the siblings' Jaeger that stole the show following an extremely graphic final battle in Shiganshina.

However, with such a detailed and deep lore as Attack on Titan, some fans may need why Zeke and Eren betrayed each other in episode 78 explaining.

Each brother plays the other…

After Eren is brutally decapitated by Gabi using the Anti-Titan sniper rifle, his head is caught by Zeke before he passes away; the two brothers make physical contact and enter The Paths.

However, when Eren awakens in The Paths, Zeke has been there for several years, perhaps even decades, and is chained down.

“It feels like I’ve been waiting years for you to recover and wake up…Your head was blown off by Gabi, but you made contact with me before you passed on. We succeeded. We obtained the power of the Founding Titan.” – Zeke, Attack on Titan episode 78.

He explains that Eren has the Founding Titan’s power and is, therefore, the only person who can move freely in The Paths and control Ymir, i.e., the young girl who builds Titans.

Zeke then tells Eren to instruct Ymir to euthanise all Eldians but in a shock twist, Eren decides against following his brother and Yelena’s plans.

“Euthanize every last Eldian…There’s no way in hell I’d go along with such a messed-up plan! Sorry, Brother. I was only playing along in order to get here.” – Eren, Attack on Titan episode 78.

However, the entire conversation has been a trick by Zeke, who reveals that not only has he nullified the vow renouncing war but also that he controls Ymir as he is a descendent of Royal Blood.

Why did Eren betray Zeke in Attack on Titan episode 78?

To put it simply, Eren betrayed Zeke because he is not in support of their plans to euthanise every Eldian on the planet until the end of time.

This was something that was foreshadowed by Armin over the previous two episodes, who had repeatedly claimed that Eren had alternative motives that could explain his betrayal of the Scouts.

When asked why Eren went along with their plans, Armin argues that:

“The Founding Titan’s power is ultimately his to use! When Yelena brought up the idea to him, he had no other choice! If he refused, who knows what Yelena would’ve done? But if he goes along with it and convinces them he’s their ally, he can protect the island with the rumbling! Nobody will dare touch Paradis Island for 50 years!” – Armin, Attack on Titan episode 76.

Eren had planned this from the start, since before even the raid on Liberio when he met with Zeke posing as an injured Marley soldier. His objectives were simple; ally with Zeke and Yelena, make contact and connect to the Founder Ymir in The Paths, gain her power and use it to save Eldians around the world.

When Zeke asks Eren why he betrayed his brother and their plans, he simply responds: “Because I was born in this world.”

Why did Zeke then trick Eren?

Zeke was anticipating that Eren would betray him and so set up the entire conversation in The Paths.

This was not only done to confirm Eren’s true intentions to Zeke, but to give Eren an opportunity to understand what took Zeke years (or perhaps decades) to realise when in The Paths.

“In the time it took for you to wake up, I learned many things. The Founder can make anything, even these earthen chains. As long as I, with royal blood, wills it.” – Zeke, Attack on Titan episode 78.

Zeke then argues that Eren is still against his euthanisation plan because of their father and the memories instilled in his mind from generations past.

“I thought as much, Eren. I hoped, if anyone, you would understand. Is this the result of Father’s brainwashing again?!” – Zeke, Attack on Titan episode 78.

However, Erens betrayal and subsequent tricking by Zeke still hasn’t shaken the bond between them.

“You and I are tragic victims born by that vile father. But I had another father who saved me. You need somebody to save you, too. I will never abandon you. I’ll fix you with the Founder’s power…When I save the world, it’ll be with you! – Zeke, Attack on Titan episode 78.

Is Zeke the Founding Titan then?

Without giving away any spoilers from the original manga series; at the time of writing in the anime, Zeke is not known to be the Founding Titan.

However, after his time in The Paths with the Founder Ymir, he does possess the Founding Titan’s powers after nullifying the vow renouncing war.

As he explains in The Paths, the Founder Ymir has incredible power but is only a servant to those with royal blood, i.e. Zeke, with Eren only being the ‘key’ to getting them to Ymir.

“I’m here without being tainted by the First King’s ideals. And in the mind-numbing time I spent with the Founder, I managed to nullify the vow renouncing war. Though possessing tremendous power, the Founder is a slave with no will of her own. She believes those with royal blood are her masters and obeys them.” – Zeke, Attack on Titan episode 78.

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