Attack on Titan blew everyone away with its finale, but there’s still a ton we don’t fully understand. Even with both the anime and manga wrapped, fans are still rewatching scenes, dissecting every piece of dialogue, and arguing for hours online. From character fates to the truth behind the Titan curse, Attack on Titan left behind a bunch of mysteries that never got a full closure.
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If you’re deep in the Attack on Titan fandom, you’ve probably seen the endless Reddit threads and theories trying to crack its biggest mysteries. While the series gave us several moments that brought us all together, others were left deliberately vague, and that’s part of why it’s got such an active fandom even a decade later. So, here are seven unanswered questions from Attack on Titan that fans can’t, and probably won’t, stop debating anytime soon.
7. Who Does Mikasa End Up With?
Mikasa’s love life is still one of the biggest debates in the AoT fandom, with many of us wondering who she actually ends up with. In the final episode, we see her visiting Eren’s grave, wearing the same red scarf he wrapped around her when they were kids. Later on, in the end credits time-lapse sequence, she disappears for several seasons, hinting that she tried to start a new life away from all the pain, and eventually returns with a man and a child, whose identities are left ambiguous, creating one of the most talked-about mysteries in the series.
A lot of fans believe the man is Jean, based on his hair, silhouette, and feelings for Mikasa dating back to their Training Corps days. While others argue she never truly moved on from Eren. The anime adds even more mystery by showing Mikasa being buried with a ring on her finger. Though it’s unclear whether she found love again, it’s clear she loved Eren until the very end.
6. How Does the Titan Serum Actually Work?
The Titan serum has always been one of Attack on Titan’s biggest mysteries for me, with the show only telling us it contains Titan spinal fluid that turns Subjects of Ymir into Pure Titans when injected, but never explaining the actual science behind it. There also seem to be different types of serums that create different Titans or abilities. However, the show never fully explains how these variations work or how Marley learned to control the process, leaving us fans with plenty to debate.
Another interesting detail is that we know drinking the serum can work as well, like when Eren bit into the “Armor” serum to gain hardening abilities. But when Rod Reiss licked some meant to grant the “strongest” Titan abilities, he ended up transforming into an unusually large, disfigured 120-meter Titan. This could suggest that improper use can lead to unpredictable results. But then why didn’t Eren didn’t have a botched transformation when he did the same? It’s possible his being a Titan shifter already protected him against potential negative consequences, although it seems like we won’t ever know for sure.
5. Why Didn’t Reiner and Bertholdt Go After Eren’s Basement?
Even though Reiner and Bertholdt knew there was some crucial info hidden in Eren’s basement, they never attempted to investigate it during their years as undercover cadets. Many fans believe they were mostly just focused on locating and retrieving the Founding Titan, overlooking the basement’s importance. Others think Marley may not have known about the basement at all or considered finding the Founding Titan more urgent.
It’s also possible that getting to the Shiganshina District after Wall Maria fell would’ve been super dangerous, since the area was constantly patrolled by the Survey Corps. As Reiner and Bertholdt were undercover, we can see how any attempt to reach the basement could have been incredibly suspicious. But the show never directly addresses this decision, leaving fans to wonder how things might’ve played out had they discovered Grisha’s secrets earlier.
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4. Why Doesn’t Eren Awaken His Titan During Training?
Throughout his time in the Cadet Corps, Eren never accidentally transforms into a Titan, even though he had the power dormant inside him. We’ve learned from the series that turning into a Titan requires both an injury and a clear goal in mind. Since Eren had no clue he even had these powers, it’s possible he simply never met both these conditions at the same time during training.
But some fans believe Grisha Yeager might’ve used the Attack Titan’s memory manipulation to temporarily suppress Eren’s abilities until they were actually needed, like when he got swallowed by the Titan. Others argue that his training injuries were just too minor, and his healing abilities kicked in before anything could happen. Either way, the dormancy of his powers made for a dramatic reveal when he first transformed to save his own life; though fans still debate whether it was all just a coincidence, part of Grisha’s plan, or even a set-up by future Eren himself.
3. How Did Eren Manipulate Mikasa’s Memory if She’s an Ackerman?
One of the most confusing contradictions in the anime is the scene where Eren appears to share a dream or memory with Mikasa, even though Ackermans are supposed to be immune to the Founding Titan’s memory manipulation. Some say that Mikasa’s mixed heritage might’ve made her an exception. Seeing as she’s only part-Ackerman and also connected to the Hizuru clan.
Other fans point to her recurring headaches in the final part of the anime as signs that her mind was fighting against the manipulation. There is also the theory that Eren actually never suppressed or altered Mikasa’s memory. Instead, fans speculate that he pulled her into the Paths at the very last moment, creating a shared moment with her before she had to return to the real world and kill him.
2. What Really Is the Centipede That Gave Ymir Her Power?
The origin of all Titan powers, sometimes called “the Source of All Living Matter” or “the Sentient,” is this shining, centipede-like creature that attached itself to Ymir Fritz when she fell into a tree. This entity granted her Titans abilities and started the whole Titan cycle. After Mikasa kills Eren and everyone turns back to human, we get a quick glimpse of the “centipede” seemingly being destroyed, but its exact nature remains unexplained.
In a conversation with Armin, Zeke suggests that Ymir fused with the creature to protect herself from pain and death, creating this big, powerful, immortal body. But even this is just a theory. It’s also unclear if the creature was actually fully destroyed or just returned to a dormant state. The series never even reveals whether this entity had consciousness or any specific goals of its own, leaving it as one of the biggest mysteries that fans continue to discuss.
1. Could the Titan Cycle Begin Again?
After Eren wipes out over 80% of the world’s population, his death brings an end to the power of Titans, but the series never really confirms if that change is permanent. Three years later, we see Armin, Reiner, Jean, Connie, Pieck, and Annie working as peace ambassadors between Paradis and the rest of the world. So yes, things seem hopeful. But the anime’s ending definitely leaves the door open for the return of the Source of All Living Matter.
This uncertainty ties into one of the show’s central questions: can humanity ever truly break free from endless cycles of violence and hatred? A lot of fans point to the final scene, where a boy and his dog stumble upon a tree that looks eerily similar to the one that started Ymir’s story, as a subtle sign that the Titan curse might not be gone for good. With no real closure, we’re left to draw our own conclusions about whether the story’s truly over, or if history is just waiting to repeat itself.
