Did Eren Yeager really eat his own father in Attack On Titan? The Attack On Titan manga quickly became a cult hit after it debuted in 2009. This Hajime Isayama created series is set in a world when mankind shelters behind the walls of a vast city to protect themselves from man-eating "Titans." A long period of peace is shattered when the outer wall is breached by a Colossal Titan. Main character Eren and his friends join the Survey Corps to fight back, but as the story progresses the history behind the giants, the city and the larger world gradually becomes clear.
Attack On Titan became a major success thanks to the 2013 anime adaptation, which made for addictive viewing. The show's vivid action and absorbing narrative hooked fans and it will come to an end with the upcoming fourth season. The franchise has also spawned various video games and two live-action movies from Japan, though these adaptations were greeted with lukewarm reviews for their many changes to the narrative. A live-action American movie is also in the works, but there's no confirmation on when it will move ahead.
One of the best things about Attack On Titan is just how fleshed out and dense the lore of the franchise is, though this can make it tough to condense the story for newcomers. Eren's father Grisha is an extremely important figure in the story, who secretly held the power of the Attack Titan and on the day Wall Maria was breached, is revealed to have confronted the royal Reiss family of Eldia. Frieda Reiss held the power of the Founding Titan but when she refused to help stop the Titan attack taking place, Grisha transformed and after a vicious battle, devoured her and her power; he also killed the rest of the clan besides Rod, who managed to escape.
Shortly after this, Grisha - who was nearly at the end of his lifespan as Titan Shifters only live thirteen years - took Eren out to the woods and injected him with a serum. He also gave his son the key to the basement which held all his information on the nation of Marley and his true objectives, before his son turned into a Pure Titan and ate him. This was Grisha's desire as it meant Eren inherited both the Attack Titan and Founding Titan powers. This is all revealed during Attack On Titan season 3, though Eren forgot this trauma until his suppressed memories are unlocked by Historia.
This is obviously a pivotal reveal in Attack On Titan's story and set up many key story points moving forward. It's also worth remembering Eren went from watching his mother Carla being eaten by a Titan - who later turned out to be Grisha's first wife Dina - to later being transformed into a giant and devouring his own father; that's a lot of therapy right there.