|No matter which era this Titan has found itself in, it has pushed ever forward, seeking out freedom. For the sake of freedom, it fights. Its name... The Attack Titan.|
|— Eren Kruger describes his Titan to Grisha Jaeger, as Eren recalls memories of them through the paths|
Grisha Jaeger is consumed with regret over the loss of his family and his cause, but Eren Kruger convinces him to take up his mission and retake the Founding Titan from the King who refuses to use it to save the Eldian people. To do that, Kruger passes on his Titan to Grisha, calling it the Attack Titan.
In present day, Eren Jaeger realizes that due to the "Curse of Ymir" he has less than eight years to live, and Armin Arlelt has thirteen, since he just recently inherited the Colossal Titan. They attend a military audience to go over the findings in the basement and Hange Zoë says they may have to consider the rest of the world as their enemies due to the fact the people outside the Walls fear the Subjects of Ymir. When Hange discusses the fact that Eren was able to use the Founding Titan despite not being of royal blood, he realizes that he was only able to do so because he had touched the Titan form of Dina Fritz when he did. He keeps this information to himself out of fear of what the military might do to Historia Reiss if they knew.
The Owl's Titan kills off the remainder of the soldiers from Marley Public Security in front of a shocked Grisha Jaeger. After they are all dead, he leaves his Titan and climbs back on the wall where he cuts Grisha free of his bonds. He introduces himself as Eren Kruger and explains that he possesses one of the Nine Titans. Like Grisha, he is a Subject of Ymir. He pretended to be a Marleyan and infiltrated Public Security, passing the blood tests with help from a doctor.
Kruger says that Grisha had done well, though Grice was right to lament his results. Grisha admits that he has been a poor husband and father, and wonders how it is that he is the only one of the prisoners still standing as a human. He grabs Kruger with the mangled stumps of his hands hard enough that the wounds begin to bleed through his bandages. Grisha demands to know why Kruger did not save his wife Dina since she was of royal blood. If Kruger had gone on his rampage sooner none of the Restorationists would have been turned into Titans.
Kruger sags to his knees and admits that it was not just fellow patriots he had tortured. He had cut the fingers off the hands of thousands of Subjects of Ymir, including women and children, and had them transformed into Titans. He believed it was all in service of Eldia. Kruger informs Grisha he does not have much time left, and so he is entrusting him with his final task.
He tells Grisha that if not for that day they first met, Grisha probably would not have hated Marley as much as he does. His hatred was part of the reason Kruger chose him. He recognized Grisha's hatred as a child because it was similar to Kruger's own. When the King left, the royal family members who stayed behind staged a revolution and Kruger's father was a part of it. However, they failed and Kruger survived by hiding in a closet as a child while his family was burned alive.
Ever since, he wanted revenge on Marley and to restore Eldia, but all he found himself doing was cutting off the fingers of fellow patriots and then casting them from the wall to be turned into Titans. Because of this, his true identity was never discovered.
Grisha asks about this final task and Kruger explains that he wants Grisha to infiltrate the Walls and retake the Founding Titan, using the Titan he will inherit from Kruger. Grisha realizes that this means he will have to eat Kruger, and the Owl does not deny it. The Founding Titan will have to be taken the same way. Kruger cannot do this himself, because those who inherit one of the Nine Titans will die in thirteen years and he already inherited his power thirteen years ago.
In the present day, Eren Jaeger calls this the "Curse of Ymir." That was how long Ymir Fritz had lived after awakening to the Power of the Titans. Armin Arlelt realizes that this means he has only thirteen years left, and Eren has less than eight. Mikasa Ackermann is saddened by this and refuses to believe it. Eren also brings up the fact that if one of the Nine Titans dies without the power being passed on, the power will be inherited by a baby yet to be born to a Subject of Ymir. All Subjects of Ymir are connected by something they cannot see. According to Eren, one inheritor called them "paths."
The paths allow the transfer of the blood and bone that makes up a Titan's body, and sometimes thoughts and memories can be transferred as well. All paths cross at a single coordinate, the Founding Titan.
In the past, Grisha asks the Owl who Ymir really was, and Kruger admits that no one really knows. Everyone has a different truth, whether she was a pawn of the devil or a god-given miracle. All that matters is what people believe. Dina's royal heritage was not a convenient lie though. She truly was a member of the royal family, which was why Kruger hid her heritage from Marley. He did not want her to spend her life giving birth to royal children for their enemies.
However, Grisha is reluctant to take on Kruger's mission. Watching the death of the man who had killed his sister was unbearable, even knowing what he had done. If Grisha had known the price of freedom, he never would have paid it.
Kruger tries to motivate Grisha with a photo of his family, and when that fails to work he prods at Grisha's pride and sense of worth, but Grisha says that it is pointless to make him recall his hatred. All he has left are his sins, and the Owl says that is enough. The main reason he picked Grisha was not his hatred, but that he left the walls that day as a child. If Grisha had not, he probably would have inherited his father's clinic and his sister would have grown up and married, but the fact remains that he went outside the wall. Both he and Kruger have sins to atone for and they must push on until the price for their actions is paid.
Grisha turns in anguish and sees the photo of himself, Dina, and Zeke. He takes the photo from Kruger, and Kruger explains that each of the Nine Titans has a name. His is the Attack Titan.
Back in the present, Hange Zoë comes to let Eren out of his cell and finds him muttering to himself about the Attack Titan. She wants to know why that is, but Levi Ackermann passes it off as a symptom of Eren being fifteen and going through a phase. To Eren's surprise, Levi opens his cell and lets him out, even though he is supposed to be confined for another ten days as punishment for insubordination. Armin adds that it was cleared by Premier Dhalis Zachary and Hange says it would send a bad message if they jailed the heroes who defeated the Armored and Colossal Titans. After Eren and Mikasa are out of their cells, Levi tells them to get dressed for an audience.
In Trost District, Historia Reiss reads the letter Ymir left her via Reiner Braun. Ymir apologizes for leaving Historia behind and explains that it will not be long before she dies. She wishes that she had no regrets, but there is one; that she was unable to marry Historia. On touching the letter, Historia gets a sudden flash of memories, from Ymir's past up until a vision of Ymir chained in a white gown in a chamber similar to the underground chapel used by her family to transfer the Founding Titan.
Surprised, she asks Hange if that is all to the letter, and Hange confirms that it is. Though Hange doubts Ymir was able to leave them any useful information through the letter, Jean Kirschtein asks if there could have been a secret message that only Historia would understand. Historia doubts that Ymir would have tried something like that and laments that Ymir never allowed her to get close to her.
She brushes away her tears as Eren, Mikasa, Armin, and Levi are shown into the room. Her former squadmates bow before her and call her "majesty," embarrassing her. She feels she did not get to do much while they were on their last mission, but Armin assures her that it is an important duty just for her to stay alive.
The military hearing begins as the senior officers go over the revelations discovered in Grisha Jaeger's journals. Hange summarizes the mission to Shiganshina District and that they can no longer consider Titans as their only enemies. Unfortunately they must consider another civilization, possibly the world, as their true enemy. The people of the Walls are members of a special race that can turn into Titans and there is a belief outside the Walls that they may try to rule the world again, and this belief makes others wish to eradicate them.
In the past, Kruger tells Grisha that the Eldians are done if Marley ever gets a hold of the Founding Titan. Though the King threatened the rest of the world if it interfered, in truth it was a bluff to buy a period of peace, and the King has no intention to fight. He made a vow to renounce war together with the Founding Titan and would willingly allow his people to die if Eldia sinned again. Kruger does not consider such a man to be a true King, which is why they need to take back the Founding Titan.
In the present, Hange discusses Grisha's mission and how he ultimately achieved it, handing the Founding Titan over to his son, Eren. Only someone who is of royal blood can fully utilize the Founding Titan. However if such a person possesses the Founding Titan, they are enslaved by the King's ideals and are unable to act against them. Since Eren was able to command Pure Titans once, Hange suspects that it is possible for someone not of royal blood to use the Founding Titan's power.
Just then, Eren remembers what happened when he commanded the Titans, and that he had punched the Titan form of Dina Fritz, who was of royal blood. He suddenly stands and shouts in the middle of the hearing as he realizes why he was able to control the Titans. The other members of the Scout Regiment stare at him, but he says it is nothing and sits back down.
Hange passes it off as Eren going through a phase, but in truth, Eren realizes that if he touches someone of royal blood while they are a Titan then he might be able to use the Founding Titan's powers. It is only a possibility, but he does not want to think of what the military might do to Historia if they knew.
In the past, Kruger prepares the Titan injection to give Grisha, and tells him to have a family again. Even if most people lose their memories shortly before the time they transform into a Titan, that is not always the case, and it is possible someone else may see them later; a wife, a child, a neighbor. Grisha should love someone within the Walls so the pattern of violence does not repeat. He will have to see his mission through, if he wants to save Mikasa, Armin, and everyone else.
Grisha asks who Mikasa and Armin are, and Kruger admits that he does not know, nor does he know whose memories those are.
Currently Publicly Available Information
The Nine Titans
The true identity of Intelligent Titans stemming from a power exceeding human comprehension that sleeps in Subjects of Ymir. Said power is inherited along with memories through paths which transcend space and time. The 'Coordinate' where all paths intersect is the Founding Titan.