In this blog post i will present my theory concerning the ending of Attack on Titan. I will be providing evidence regarding the fates of the main cast, the world and the general direction of the plot. This will be a long post, so be prepared for a lot of reading.
The dual nature of the world and the battle against Eren
It has been very clear for a long time now that Isayama loves to pit concepts against each other, showing the place that it's one has in the characters and the world he has created. There can be no better example than Mikasa's personal understanding of the universe she lives in: "This is a cruel world, yet so beautiful". This right here is the essence of the series. Time and again, it's proven to be true. In Attack on Titan, it's only the winners who survive. So, what does that mean for the series?
The "hidden" meaning behind this worldview is explained in an articulate manner by none other than Uri Reiss here: . Violence can not stop existing. So long as human walk this earth, violence will always be present. Killings, war, murders, these things won't ever really stop. Humans, from the beginning of time have resorted to violence to put an end to their problems. It's wired into them. Does that mean though that that's all there is to them? That there is no other way than to hack ourselves to pieces? No. That's not it. But, it takes a miracle for that.
However, how often do miracles happen? Even when people have the best intentions, in the end, violence seems to prevail. The Survey Corps went to Marley to find supporters and found themselves witnesses to an absolute disregard of their humanity. Armin tried to negotiate with Bertolt in Shiganshina and almost got himself killed. In the end, he killed Bertolt. In the most recent chapters, the Alliance's attempts to resolve things peacefully with the Yeagerists ended in disaster. They are killing each other again. Finally, Eren himself didn't want to resort on the Rumbling, yet he decided to murder every human on Earth, beyond Paradis.
With all these examples of violence coming out on top, it would seem that there is no room for negotiations to take place between the Alliance and Eren. I mean, how could they even convince him. We are talking about the most stubborn person in the universe. Not only that, Eren has also seen the future. He knows what's going to happen (more on that latter). Against an "enemy" like that, how can they win? The answer is miracles. A miracle will happen and stop Eren. That miracle is Mikasa's relationship with Eren.
Compared to every other relationship in the series, the one between the two most prominent characters in the series (Eren has appeared in 115/128 chapters, while Mikasa in 114) is the most complex and the one that expresses this duality better than any other. For Mikasa, Eren used to represent the beautiful part of the world . Until recently, Mikasa used to see Eren solely for the person who wrapped his scarf around her. This of course changed dramtically in chapter 112 with Eren claiming that he hate Mikasa's guts more than anything else in the world. This, along with Eren's goal to annihilate the entire world force Mikasa to see him for who he really is. From chapter 123 onwards, Eren becomes for Mikasa a living representation of everything that's cruel and beautiful in the world, all at the same time.
So could she have stopped him? Could Mikasa have prevented this slaughterhouse, had she spoken the truth to Eren? For that, we'll have to take a look at Eren. Eren, started the final portion of the story clad in an armor of mystery. What are his goals? What are his motivations? Did he really change that much? Concering the last question, his friends thought so at the opening chapters of this arc. Even Mikasa herself wanted to believe that Eren had changed. That he wasn't the same man he once was. Well, that didn't go very well. Mikasa eventually realizes that Eren hasn't changed at all. At his core, he is still the same guy who murdered brutally two adult men, without even considering them as human beings. Eren himself seems to agree with that notion. He doesn't think he has changed. This provides some sort of solace to him, because it means that there was nothing else he could have done. Isayama said some interesting things about this topic: Ultimately, I don’t think the series passes judgment on what is “right” or “wrong.” For example, when I read Furuya Minoru’s “Himeanole,” I knew society would consider the serial killer in the story unforgivable under social norms. But when I took into account his life and background I still wondered, “If this was his nature, then who is to blame…?” I even thought, “Is it merely coincidence that I wasn’t born as a murderer?” We justify what we absolutely cannot accomplish as “a flaw due to lack of effort,” and there is bitterness within that. On the other hand, for a perpetrator, having the mindset of “It’s not because I lack effort that I became like this” is a form of solace. We cannot deny that under such circumstances, the victims’ feelings are very important. But considering the root of the issue, rather than evaluating “what is right”…to be influenced by various other works and their philosophies, and to truthfully illustrate my exact feelings during those moments - I think that’s what Shingeki no Kyojin’s ending will resemble. This pretty much means that Eren is not free, despite his declarations. He even says that he had no choice, but to act the way he did.
But, that's not all there is to him. While capable of extreme violence, Eren has also been to showcase equal amounts of kindness. His relationship with Mikasa, symbolized by the scarf he gave to her, is that link to Eren's humanity, his kindness. It's also the bond that he tries his hardest to destroy post-timeskip. Even more than what he does to Armin, Eren tries to cut all ties with Mikasa, culminating with him ordering Louise to throw away Mikasa's scarf. This is what Eren needs to do in order to achieve his goal. In order to change something, it's mandatory to leave behind what one holds dear and become a devil. For Eren, it's his his relationship with Mikasa and, to a significant, yet lesser extent, Armin.
However, this presents a weakness. A weakness than can, and will, be exploited. Mikasa is an Ackerman. That means that she is immune to the powers of the Founding Titan. She can't be mind controlled, she can't have her biology altered . She is free to fight Eren as an equal. Isayama himself has said that there is no such thing as an "Ackerbond" here: They are all part of the same Ackerman bloodline. However, their reasons for protecting their respective counterparts don’t have anything to do with the bloodline itself - it’s just their nature (laughs). Within the story, Mikasa and Levi almost have the guardian/knight-like roles, right? That’s because they encountered the existence of a “boss”-like individual (T/N: Isayama interestingly uses the exact katakana “ボス” - “boss” here), and the desire to work for that person is very in line with their personalities.
With many clues presented in the manga, both in previous arcs,, but also in the most recent one,  , it's a certainty that the final showdown in the series will be between Eren and Mikasa. The rest of the characters will "fall" to Eren's coordinate. Stopping him will be impossible for Armin, Jean, Reiner etc. Magath is not important enough to "defeat" Eren and Levi has Zeke. So that leaves Mikasa. If Mikasa is really determined to stop Eren (narrative causality dictates that she will be), Eren's only option to succeed will be to kill Mikasa. Concidering the nature of their relationship and their interactions, Eren killing Mikasa is 100% impossible to happen.
So we go back to the one important question i previously left unanswered. Could Mikasa have stopped him before? My answer is yes. She could. Which is why Isayma features this scene so prominently in the same chapter. And, going by the theme of violence vs miracles in the series, i guess that Mikasa telling the truth to Eren will be very important in stopping him. Eren has already chosen the road of violence. Now it's time for a miracle. Like the one that happened many years ago .
Time travel in AoT
Yes, time travel exists in the series. Information travels back and forward in time. What's going on here is called a "causal loop". Eren going inside the paths and sending his memories back in time led to Grisha killing the Reiss family. Because in his own life, Eren knew that Historia would become the queen and that she was the sole Reiss heir that wouldn't eat him . The past was modified in order for the present to be as it is. Well, modified might not be the correct word, since there was only ever one way the events could have gone down. The one that we've seen. The future is written in stone. The future cannot be changed. Everything that Eren has seen will happen, solely because he has seen these events happening and because he believes that these events cannot be altered. It's the "universe's" way to present the timeline. Every action that could have altered the future, simply doesn't happen. Part of that is Mikasa's inability to tell Eren what she really wanted to, back in Marley. In Game of Thrones terms "the ink is dry".
Eren is not free in the degree that he knows the future. He doesn't have a choice. Nevertheless, he doesn't have complete knowledge of it . That is also intentional and i will explain how now. Isayama puts emphasis on the fact that Zeke didn't see the part where Eren kills their dad . It's also pointed that after Grisha killed the Reiss family he regretted helping Eren. However, in the end he gave him the power. Why?
Well, because the one sending the memories to Grisha and Eren, is none other than Eren himself from the future. Eren, after everything is said and done, close to the story's conclusion and before his death, Eren will enter the paths once again and send the entirety of his memories to Grisha, which will prompt his father to eventually give him the power. Not only that, Eren will influence all the events of the past that he needs to influence, in order for some things to happen. Two of them (farfetched i know) are the existence of Asians  inside the Walls and Armin being in possession of the book about the outside world. That's because the Eren from the future will know of their important roles in his life and in the events of the story.
Peace and the fate of the cast
So, i talked about how Eren will go back in the paths to do his job and ensure the present/future before his death. What i mean by this is that Mikasa won't kill Eren, but Eren will still die. And he fail in destroying the world. Because that's really not his mission. Eren's mission, and the reason that Grisha eventually gives him the Attack Titan is this:. To save Mikasa, Armin and everyone else. And this can't be accomplished by annihilating humanity. That should have been obvious from the time Mikasa and Armin joined the Alliance. Their continued survival and the rumbling do not go hand in hand.
So, moving on to the fates of the cast. After Eren's "defeat" at Mikasa's hand, a ceasefire will occur between Marley and Paradis. Magath will negotiate with the remnants of the Survey Corps, mostly Armin and a peace treaty between the two countries will be signed. However, in order for Marley to be certain that Eren won't ever try to kill them all again, they will demand for him to eventually give his titans to someone whom both parties can trust. Paradis needs the Founding Titan in order to be entirely sure that they will be safe, while Marley being weakened by the continuous war also need the Coordinate. The titan powers can't stop existing, unless Eren murders the entire world, which is not going to happen. Eren will decide that the person to take his powers will be Gabi Braun.
The prospect of Eren having a successor is featured prominently in this arc,. We know Eren doesn't want any of his friends to get his powers. With the amount of parallels between Eren and Gabi being so many, there is not a single person better suited than her to become the Attack Titan, especially after her recent character development and considering the fact that Falco has also become a titan. As a matter of fact, this is the only route her character can go on. She can't help in the battle right now since she is not even fighting and she is a Subject of Ymir, meaning that she is useless against Eren. That's the most effective use of her character. As a side note, Gabi has the most screentime in the series, along with Eren, ever since her introduction in the Marley arc. She has appeared in 32 chapters, equal to Eren and 1 more than Mikasa.
Speaking of Mikasa, after defeating Eren and learning the truth about how he lied his ass off when talking to her, she will accept that Eren needs to die for humanity. Part of her character arc has always been to survive the deaths of her loved,  ones and keep moving forward and this is what's going to happen. She is the girl who says "See you later, Eren" and the reason her face is covered is this:. It's to cover her tears. She will get a scarf-rewrapping moment with Eren as he promised to her and she will then leave immediately to Hizuru, to become the Shogun there and ensure that her richer nation will aid Paradis financially, without ripping the island off.
Moving on to our favorite blond, Armin will also survive the series and continue advising Eldia for his remaining years. He will be the one to figure out the right story to tell to the people, presenting his friend as the ultimate enemy a la King Karl Fritzhttps , the first King of the Walls (even though Eren will kill the Colossal Titans, before Mikasa's blades reach him), ensuring humanity's continued survival .
Sufferboy-Reiner will make it out alive and i believe that he will spend his remaining days trying to unite the Eldians of Marley with the Marleyans. Annie will get to reunite with her daddy and won't do anything more, same as Pieck really. Falco and Gabi are a duo, so they will stay together. Magath will take the reigns of the negotiations between Marley and Paradis from the marleyan side and will try his best to create a better world for the Eldians.
As for our remaining 104th and SC characters, well, Jean will become the Commander of the Survey Corps after everything is said and done. He won't be with Mikasa (mainly because she is in love with Eren and because she will leave Paradis forever) and he won't get his dream house (too expensive for the SC and only the MPs get to live in the Central District), but he will become a good commander. Connie will die in the next few chapters as foreshadowed in the railroad sequence from chapter 108. Just like Sasha really. Sasha was the bigger idiot of the two so she dies first. Hange will also die, probably in the next couple of chapters (too many death flags, especially with that sequence here) to make room for Jean.
Zeke and Levi, well, i don't know about them. Zeke will probablt die, but i'm not sure about Levi. I don't think he will bite the dust. Historia will, however, survive and i'm positive that it's her child that's depicted in the final panel of the series.
For the irrelevant characters, Floch is 100% going down, while Keith Shadis will probably take Zackley's position. Annie's dad and Reiner's mom will survive. Same probably with Eren's grandparents.
In general, we don't have a lot of deaths left, however the series will end with a bittersweet tone. The world will be in a better state than in the beginning of the series, though with heavy rebuild being necessary and without the racism being gone. The end will show the first few baby steps of the world towards a new future. However, in order for this future to come to fruition, Eren will have to die, Mikasa will have to let him go and never get to live the life she wanted, Armin will be left with 9 years on his term, Zeke probably dead, millions of people dead, Hange and many other members of the army dead and so on. In other words, an ending where none of the main characters gets exactly what he/she wanted, but their sacrifices will make it so that the next generations won't have to face such tragic circumstances. A fitting conclusion for the series.