Eren gets the Founding Titan by inheriting it from his father, Grisha Yeager, who had previously stolen it from the Reiss royal family and then passed it to Eren by turning him into a Titan and having him eat him.

How Did Eren Get the Founding Titan? (Quick Scoop)

1. The Power Before Eren: Frieda Reiss

  • The Founding Titan originally rests with the Reiss royal family, specifically Frieda Reiss.
  • The Reiss family secretly passes the Founding Titan down through generations and lives hidden from the public in an underground chapel.

In the story, Frieda visits Historia in secret, acting like a kind big sister while secretly carrying the most powerful Titan of all.

2. Grisha Steals the Founding Titan

  • When the Colossal and Armored Titans attack Shiganshina and chaos breaks out, Grisha realizes the royal family will do nothing to save humanity inside the Walls.
  • He tracks the Reiss family to their underground chapel and begs Frieda to use the Founding Titan to stop the Titans and save his family and people.
  • Due to King Fritz’s “vow of renouncing war” that binds the royal line, Frieda cannot act aggressively with the Founder’s power, hesitates, and refuses.
  • Grisha, driven by desperation and his mission as an Eldian restorationist, transforms into the Attack Titan, slaughters most of the Reiss family, and defeats and eats Frieda, taking the Founding Titan from her.

This is one of the darkest hidden moments in the backstory: the “heroic father” Eren remembers is actually someone who wiped out a royal bloodline to seize the Founder.

3. Grisha Passes Both Titans to Eren

  • After taking the Founding Titan, Grisha now holds two of the Nine Titans: the Attack Titan and the Founding Titan.
  • Knowing that Titan shifters only live 13 years after inheriting a Titan and that Marley is a massive threat, he decides to pass everything to his son.
  • In the woods near Shiganshina after the fall of Wall Maria, Grisha injects Eren with a Titan serum, turning him into a mindless Pure Titan.
  • In that form, Eren eats Grisha, unknowingly devouring his father and inheriting both the Attack Titan and the Founding Titan in one moment.

At this point, kid Eren has no idea what happened. His memories are blocked, and he only “wakes up” later in a refugee camp, believing his father just vanished.

4. When Eren (and We) Learn the Truth

  • In early seasons, everyone thinks Eren only has the Attack Titan , because the Founding Titan is still a mystery and its power doesn’t fully activate.
  • Later, through Rod Reiss’s explanations and hidden memories, it’s revealed that Grisha killed the Reiss family and ate Frieda, stealing the Founder.
  • Even later in the series, Eren’s recovered memories confirm that he ate Grisha as a Pure Titan and inherited both powers at once.

So the clean answer to “how did Eren get the Founding Titan” is:

  • Frieda Reiss → eaten by Grisha → Grisha Yeager → eaten by Eren.

5. How Eren Can Actually Use the Founding Titan

Getting the Founding Titan is one thing; using it is another.

  • The Founding Titan’s full powers usually require royal blood.
  • Eren is not of royal blood, so at first he can only activate its abilities under special conditions, like touching a Titan with royal blood.
  • A key moment is when he punches the “Smiling Titan” (Dina Fritz, a royal-blooded Pure Titan), and suddenly commands other Titans, showing the Founder’s power briefly.
  • Later, he realizes he can fully unlock the Founder by making contact with his half-brother Zeke, who does have royal blood.

This is why so much of the final arc revolves around Eren and Zeke physically meeting—Eren already has the Founding Titan, but he needs royal blood to unleash its full potential and trigger events like the Rumbling.

6. Forum/Trending Angle (Spoiler Context)

Even years after the anime ended (with the final part airing in 2023), “how did Eren get the Founding Titan” still trends in discussions because:

  • The series reveals the truth in pieces: first Eren’s Titan, then the Reiss family, then Grisha’s massacre, then Paths and Ymir.
  • Many viewers miss the specific chain of inheritance or mix up “when he became the Founding Titan” with “when he used its full power”.
  • Episode breakdowns and wiki entries keep revisiting this topic, especially around Eren’s final skeletal Founding Titan form and the Rumbling.

A common way fans phrase it now is:

“Eren always had the Founding Titan from the start of the story, he just didn’t know how to use it properly until he teamed up (and clashed) with Zeke.”

TL;DR (Quick Version)

  • Grisha Yeager kills Frieda Reiss and eats her, stealing the Founding Titan from the Reiss royal family.
  • Grisha later injects Eren with a Titan serum so that Eren, as a Pure Titan, eats him and inherits both the Attack Titan and the Founding Titan at once.
  • Eren has the Founding Titan from then on, but can only fully use it when in contact with royal blood (like Dina Fritz’s Titan or Zeke).

Information gathered from public forums or data available on the internet and portrayed here.