Yeagerists

"It is likely their objective is to reunite Eren Yeager and Zeke Yeager..... and purge those who would oppose making Eren the leader."

- Hange theorizes the plan of action by the Yeagerists

The Yeagerists, also known as the 'Yeager Faction' and 'The Anti-Survey Corps Destruction Operations', are a rebel group rallied under Eren Yeager to reunite him with his half-brother Zeke and to possibly take control of the nation of Paradis.

Duty
After Eren Yeager was revealed to be in possession of the Founding Titan, many called on him to use his abilities to fight against the nation of Marley who were behind the failed Paradis Island Operation that took place over the course of several years. Preferring to use military actions over diplomacy in dealing with enemy nations, they renounced the path set forth by the Eldian Military and swore allegiance to Eren. Seeing him as a proper leader, they agreed with the 'Earth Rumbling' plan set forth by Eren and his older half-brother Zeke and vowed to make it come to pass, regardless of the cost.

Structure
Although a relatively small group, it has been noted that there are at least a hundred members. Many members of the Yeagerist movement are soldiers who were part of the Survey Corps and have had significant training in combat and espionage.