With weekly episodes of its fourth and final season now airing, Attack On Titan is recapturing the attention of fans worldwide. At the end of Season 3, the anime opened up to reveal a wider view of the history of its world, including the hidden fact that an all-important connection between the Eldian race and the Titans exists.
But after three complete seasons, the anime is now ready to uncover the true story behind the origin of the Titans and their relation to the citizens of Paradis Island. Season 4 will explore this relationship in further detail and bring the anime to its conclusion, wrapping up almost seven years of Titan mystery. But for some fans, the connection between the Eldians and the Titans remains unclear, so here's a basic rundown based on what we know at the time of writing.
The Eldians were an ancient tribe that existed over 2,000 years before the start of Attack On Titan. One day, a slave girl named Ymir obtained the power of the Titans and was used to declare war against Eldia's enemies. Eventually, Ymir became the wife of King Fritz and their children inherited her powers when they cannibalized her body upon her death. Through Ymir's children and other descendants, the power of the Titans spread to nine carriers. With their powers, they created a new Eldian Empire and took the name, "Subjects of Ymir."
Over time, Eldia raged war on all their enemies until there was no one left to fight but themselves. Eventually, King Karl Fritz decided enough was enough and devised a plan, alongside the Tybur Family, who possess the War Hammer Titan. By removing himself from internal affairs, the King threw his empire into chaos and opened up an opportunity for Eldia's enemies to take advantage of. King Fritz took this time to remove himself and most of his citizens to Paradis Island, where he used the last of the Founding Titan's powers to alter the memories of the Eldians to forget their heritage and the turmoil it caused. He created the three walls and aimed to start a fresh civilization for his people, who then lived in peace for a century, unaware of their own history.
The Eldians' relationship with Titans ultimately has two natures -- one as Shifter Titans and one as Pure Titans. Pure Titans were once Eldian humans who were accused of wrongdoing against the Marleyan nation and so were injected with Titan serum and sent into the wild. Though the Pure Titans retain their human memories they are essentially mindless and cannot act on their true, inner desires. In the Return to Shiganshina Arc, Ymir reveals her personal experience as a Pure Titan in a letter. She explains that she regained her humanity by eating Marcel Galliard, Marley's possessor of the Jaw Titan, but up until that point, she could do nothing of her own volition.
Shifter Titans are of an entirely different nature and are the "true" descendants of the first Ymir. A Shifter Titan is one of the legendary "Nine Titans" that can shift between human and Titan form. They can control and even order Pure Titans to do their bidding, which is why the Shifter Titans are excellent military commanders. Unfortunately, any person who inherits a Shifter Titan is bound by the "Curse of Ymir," which dooms them to only 13 years of life after their inheritance. What's pretty incredible about the Shifters, though, is that they are able to access the memories of all the people who held that Titan before them -- allowing them to delve into the depths of history.
Overall, the Eldians are inextricably bound to the Titans, no matter how detached they are from their past. Their past, present, and ultimately, their future depends entirely on the use or misuse of these Titans. That connection is as intricate as it is vital to the overall plot. Where once Attack On Titan relied on its characters' knowledge to bring the story forward, now the anime must use its own history to complete the story that started airing almost a decade ago.