For those who cannot remember well, Floch Forster used to be part of the Survey Corps before he became a Yeagerist. He was first assigned to Squad Klaus. Only he, Hange Zoe, and Squad Levi survived the battle of Shiganshina District. Fans, however, cannot remember clearly or were unsure why Floch is helping Eren to the point that he became the de-facto leader of the Yeagerists.
When Attack on Titan started, Floch was known to be a coward. But as the story progressed, his character developed and his love for the island grew after he was able to surpass the battle of Shiganshina District. He and Eren were not on the same side at first, especially after he criticized Eren and Levi for choosing Armin instead of Erwin. So what made Floch vouch for Eren now?
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Why is Floch Helping Eren?
Fans find their alliance rather odd considering they had not been on good terms in the past. But it appears that after Floch discovered the truth behind the walls and after Eren shared his great plan, the two have come to a common ground.
Eren told Floch about his plan to follow Zeke in order to activate the Founding Titan’s power. Once Floch knew the entire plan, he started to gather allies who were now called the Yeagerists. Since then, Floch has been loyal to Eren, doing everything he can for Eren’s plan to succeed. He does not have second doubts to use violence to get people to follow their plan.
When the Rumbling started, Floch took over and led the Yeagerists to support Eren. He tried to convince Yelena and Onyankopon to join the Yeagerists but the two declined which is why he planned to execute them. When this failed, he and his group focused on the Azumabito claim to force their mechanics to join sides with them.
Once again, his plan failed as Connie, Armin, Mikasa, and the rest of the protagonists attacked the Yeagerists in pursuit to get the airship and stop the Rumbling. He did his best to stop the group, even to the point of sacrificing his own life.