Over 1800 years ago, Ymir Fritz gained the power of the Titans. How though remains unclear, although some say that she made a deal with the Devil of All Earth, or she was a gift from God, or she touched the "source of all living matter." With her power, she made great advancements for her people. When she died her "soul" was split between the Nine Titans, who would go on to found the nation of Eldia. Her greatest power, the Founding Titan, would be inherited by the monarchs of the Fritz family for many centuries to come.
The Fritz family came to power as the royal bloodline of Eldia. Over these next two millennia, their lineage would be destined to remain unbroken. At some point during their rule, the Ackerman family became the guarding force of their monarchy, serving as the protectors of the monarchs.
After some time, the various elite families subservient to the Fritz family began to fight amongst each other for control of the eight Titans, though throughout the years the Fritz family maintained order with the power of the Founding Titan. However, when the 145th King of the Fritz family came into power and received the Founding Titan, he chose to abandon the never-ending conflict in the Eldian Empire and conspired with the Tybur family to end the conflict by letting the empire fall and restore Marley, a country that the Eldians have previously conquered and destroyed.
As both sides worked to dismantle the Eldian Empire that was in control, they fabricated the story of a great warrior Helos who came and was the one who had actually defeated the Eldians. The King then decided to instead move the capital of Eldia to Paradis Island off the east coast of the continental mainland. In his absence, the Marleyan minorities in Eldia seized the opportunity and sparked the Great Titan War, ultimately capturing seven of the nine Titans and overrunning the continent.
As Eldia lost more and more of its land, King Fritz gathered as many members of the Fritz family as he could to Paradis Island, along with the fleeing peoples of Eldia. However, some members of the Fritz family strongly disagreed with the King's decision to abandon the Eldian-Marleyan conflict and stayed behind on the continental mainland.
Once the Eldians willing to flee were gathered at Paradis Island, the King used the power of the Founding Titan to erect three concentric Walls around their territory on Paradis Island and erased the memory of the world from the Eldian people. From that point onward, the Fritz family in the Walls would be replaced in name by a false line of monarchs, while the true royal family would take the new name of the Reiss family.
Meanwhile, on the mainland, the Fritz family would live in hiding within the internment zones founded by the new Marleyan government, awaiting the day that Eldia would rise again.
Over eighty years after the end of the Great Titan War, Dina Fritz was the last remaining descendant of the Fritz family within Marley. She would be sent by the Owl, an Eldian spy within the Marleyan military, to join the cause of the Eldia Restorationists. There she met Grisha Yeager, who had gained significant influence in the Restorationist movement, and together they made plans to retrieve the Founding Titan from Paradis Island and restore the nation of Eldia. They married the following year and had a son named Zeke, who they insisted would be the King of Eldia.
However, Zeke ended up turning against the Restorationists at the age of seven after Grisha sent him to join the Marleyans' Warrior program, hoping that he would be a double agent. Dina would then be turned into a pure Titan, pledging in her last moments that she would find Grisha no matter what became of her. Zeke would remain in the Warrior program, rising through the ranks to become the captain of the Warriors.
Thirteen years after wandering as a Titan, Dina is among the many Titans that invade Shiganshina District in the year 845 when the Colossus Titan and Armored Titan breach the gates of Wall Maria. She wanders throughout the district until coming to the home of the Yeager family, where Carla Yeager, Grisha's second wife, lays helpless beneath the rubble of their ruined home as her son, Eren and her adopted daughter, Mikasa attempt to free her. As a Garrison soldier carries the children to safety, Dina pulls Carla out of the rubble, eating her as any normal Titan would.
Twenty years after Dina Fritz was made into a Titan, Zeke infiltrates Wall Rose and with his power as the Beast Titan turns the residents of Ragako village into Titans, spreading chaos throughout the territory for reasons unknown. He leaves Wall Rose later that night as members of the Survey Corps desperately fight his Titans.
Two months after his departure from Wall Rose, Zeke reunites with his Warrior subordinates Reiner Braun and Bertolt Hoover in the ruins of Shiganshina District. The two argue with Zeke for the sake of their comrade Annie Leonhart, who had been captured two months ago, and Zeke challenges Reiner to combat for the decision. Reiner loses, and Zeke determines that they will instead wait in Shiganshina for the Survey Corps to arrive so that they can take the Founding Titan, known to them as the Coordinate.
When the Survey Corps arrives at Shiganshina, Zeke and his Warriors battle with them both within and around the district. Zeke makes use of his Beast Titan to deal heavy damage to the Survey Corps, fatally wounding their commander Erwin Smith, but he is defeated by Levi Ackerman. During his retreat, Zeke encounters his half-brother Eren Yeager. Before they part ways, Zeke promises Eren that he will one day return to save him.
Eren Yeager and the surviving members of the Survey Corps learn of the Fritz family and their connection with both the history of the Walls and Eren's father Grisha. After learning of his father's past, Eren begins to see his father's memories in his dreams due to their shared inheritance of the Coordinate, and Eren realizes that Dina Fritz was the Titan who ate his mother.
Shortly after the conclusion of the Marley Mid-East War, Colt, the designated successor of the Beast Titan, asks Zeke for the reason behind his Titan's unprecedented abilities. Zeke acts clueless, having kept his heritage a secret from Marley and the Titan Biology Research Society.
Secretly conspiring against Marley, Zeke gains contact with Eren and orchestrates events leading up to the Liberio festival. There, the true history of Karl Fritz and Eldia's downfall is revealed to the audience, before the forces of Paradis Island attack the festival and deal a devastating blow to Marley. Zeke believes that uniting the Founding Titan with a Titan of royal blood was worth the plan's sacrifices, for its ability to restore Eldia's freedom.
- In the Q&A section of the August 2018 edition of Bessatsu Shōnen Magazine, Hajime Isayama answered a question regarding a hypothetical mixing of the Ackerman and royal bloodlines:
Q: If a child were to be born between two people from the royal family and the Ackerman family, which blood would take precedence? ("Chewing Gum" from Chiba Prefecture)
A: I think that both [of their bloodlines] would be reflected [in the child] as usual. (Isayama-sensei)
- Presumably this means that the child would have the "awakened power" of the Ackermans and can become a Titan with royal blood—able to activate the Founding Titan and fully utilize the power of the Titans—like the members of the Fritz/Reiss royal family.