The Reiss Family, Underground Chapel
This enormous underground chapel, crafted from an unknown material, sparkled like a crystal palace. It was likely created using a form of hardening ability, similar to those possessed by certain Titans.
As the true royal bloodline, the Reiss family were naturally the first to learn about the Titan breach at Shiganshina District and the fall of Wall Maria.
However, for reasons of their own, they could not publicly act. Instead, they gathered in prayer within their hidden underground chapel.
Roderich Reiss was accompanied by five children—but not among them was the "princess" of the original story, Historia. She was Roderich's illegitimate daughter, born of a maid, and therefore never acknowledged by the Reiss family. To them, she was a forsaken child.
This part of her background bears a strange resemblance to the case of Furuta.
The Reiss family's prayer session went on for quite some time. Before they could finish, however, an uninvited guest stepped into the underground chapel.
It was none other than Eren's father — Grisha Yeager.
Grisha's face showed deep inner conflict. The previous inheritor of the Attack Titan had instructed him to steal the power of the Founding Titan, but the only way to do that was... to devour the current host.
When he first came inside the Walls, his resolve was firm.
But as time passed—working as a doctor, healing others, marrying, starting a family—he had grown attached to his peaceful new life. Slowly but surely, that old determination began to fade.
And he was a doctor. How could he bring himself to kill someone, let alone eat them?
Caught in turmoil, Grisha decided he would at least try to speak with the Founding Titan's host first. If she could stop the invading Titans, then perhaps he wouldn't have to carry out the will of his predecessor.
He would avoid violence if at all possible. Especially the thought of eating another human—it was unbearable.
As soon as the Reiss family saw this stranger approach, they became visibly alarmed.
"Oh king of the people of Ymir..."
Grisha, desperate, pleaded with the Founding Titan's host—Frieda.
He begged her to stop the Titans who were devouring innocents and destroying the walls. His mind was filled with terror—Carla, Eren, Mikasa... all in danger.
Frieda was visibly shaken.
But slowly, she closed her eyes—and when she opened them again, they had turned an eerie pale violet, her expression now cold, calm, and unyielding. It was as though something had taken control of her.
With unwavering conviction, she spoke:
"Our people have committed countless sins. Today is the day we begin to atone."
Grisha's face darkened.
"Humanity is too weak to handle the power of Titans. That's why it must remain under my control, and that of every Founding Titan before me. If not, the world will fall into chaos once again."
Frieda had inherited not only the power of the Founding Titan—but the memories of all who came before her, including the 145th King Fritz.
She knew the truth behind the Great Titan War. She knew exactly what the Eldians had done to the rest of the world.
The Eldian Empire had ruled with an iron fist for over a thousand years, wielding the power of Titans to commit endless atrocities. Innocent lives had been trampled under the empire's boots.
Frieda, now burdened with that history, was crushed by guilt and sorrow.
Influenced by King Fritz's ideology—and bound by the "Vow of Nonresistance" a pact he had made with the original Titan, Ymir—Frieda came to fully embrace his pacifist beliefs.
At the same time, far in the future, Eren and Zeke were watching all of this unfold from Grisha's memories. Zeke casually spoke up.
"I feel like me and this lady would've gotten along. Too bad Dad's about to kill her and the rest of the family, huh? Guess that's just our old man for you."
Zeke waited for Eren's response, but none came.
"What, didn't you already see this memory? Don't tell me you're messing with me again."
He turned to look at Eren—only to see a terrifying expression on his face.
"That was my home... Shiganshina District. My family is there!"
Grisha suddenly exploded with emotion. "They had their memories erased by the Founding Titan! They don't even know the sins of the Eldians! They're innocent!!"
No matter how much he pleaded, Frieda remained cold and unmoved.
Her belief was firm—Eldia must perish.
And in that moment, future Eren could no longer watch. Using the power of the Attack Titan, he injected a fragment of future memories into Grisha's mind.
For a split second, Grisha could see Eren standing beside him. A memory not his own—but gifted to him.
The three Yeagers — bound by fate.
"There's nothing more to say. My mind is made up."
Frieda continued calmly. "And besides, you couldn't use the Founding Titan's power anyway. It would be meaningless."
Grisha answered immediately. "You're right—I don't have the royal blood of Fritz."
"Huh?"
Frieda flinched slightly, surprised at how much he knew.
But by now, Grisha had already seen what would happen—what he must do. Kill Frieda. Erase the rest of the Reiss bloodline. Leave only Roderich alive.
The future had already been set in motion.
Though Grisha thought he was seeing future memories because of the Attack Titan, the truth was—Eren was showing him exactly what he wanted him to see.
Grisha's face twisted with anguish and rage.
The Reiss family, even Frieda, recoiled in fear at the look in his eyes.
He let out a cry, trembling as he raised a scalpel—his arm shaking violently.
He was going to cut his hand open.
And transform into the Attack Titan.