Annihilation Melaika
He inherited the power of the Founding Titan and the Attack Titan from his father, and later devoured the War Hammer Titan during the Marley War. When Eren possesses a strong will, he can transform into a Titan up to 15 meters tall by self-harming (usually biting his left hand). He has black hair, blue eyes, elf-like pointed ears, and his body is covered in strong muscles. His will becomes the target of his Titan actions. Compared to ordinary Titans, he has unparalleled combat power, possesses a concept of martial arts, and can imitate the physical techniques taught by Annie Leonard. His teeth are also proven to be extremely hard during his battle with the Female Titan. However, in the early stages (episode 12), he lost control and showed a tendency to harm Mikasa. After achieving his goal, his body will decay Annihilation. However, this action puts a burden on Eren's physical and mental health; continuous use will weaken both his body and spirit. He possesses the ability to harden his skin and used this ability to plug the holes in Wall Maria.
After making contact with a Titan host who possesses Eldian royal family blood, one gains the authority to manipulate all Titan powers (i. e., the "Coordinate power"), and can control all Subjects of Ymir in both Titan and human forms, including issuing commands to Titans, controlling Titan bodies, and modifying the memories and physiological functions of Subjects of Ymir.
After consuming the War Hammer Titan, it can quickly create objects, and after controlling the Coordinate, it can transform into the size of Colossal Titan.
Everything was predetermined from the very beginning.
Unlike other Titans that can only view the memories of their predecessors, the Attack Titan's host can see parts of the future host's memories at special times, thus foreseeing parts of the future and influencing past events. However, everything in the future is already predetermined and cannot be changed, including the past influenced by the Founding Titan. After visiting the island, Eren attempted to change the future but failed, realizing that everything was predetermined from the beginning, and his continuous progress was simply to reach that outcome.
He is remarkably agile (killing two adults at the age of nine), but has low emotional intelligence (before meeting Mikasa, he only befriended Armin). His years of training in the Training Corps transformed Eren from a boy who only knew how to vent his emotions into a soldier. Especially in hand-to-hand combat, through practice with Annie, Eren quickly mastered the techniques Annie "taught" him, and even used them to subdue the emotionally charged Jean. In the 104th Training Corps, Eren's hand-to-hand combat skills were second only to Mikasa. However, due to his impulsive personality, Eren's hand-to-hand combat skills did not perform ideally in actual combat.
Influenced by the book about the outside world that Armin showed him, Eren's desire to leave the walls was ignited. At the age of nine, he accompanied his father on a Mikasa call, only to discover that Mikasa's family had been kidnapped. Mikasa's parents were brutally murdered on the spot, and Mikasa was nowhere to be found. The kidnappers' inhumane acts enraged Eren, and in order to rescue Mikasa as soon as possible, the furious Eren decided to confront the kidnappers alone. Upon arriving at their hideout, the enraged Eren cleverly assassinated two of the kidnappers. Just as he was about to rescue Mikasa, a third kidnapper arrived and took her hostage. In the nick of time, Eren's words inspired Mikasa's fighting potential, and Mikasa picked up a dagger and killed the kidnapper, allowing both of them to escape. Eren was severely reprimanded by his father, Grisha Yeager, for his reckless actions. Later, Eren's family adopted Mikasa, Eren even gave her his red Mikasa.
The future influences the past
After his father, Grisha Yeager Jaeger, disappeared in 845 after the Titans breached Wall Maria (later confirmed to have been eaten by Eren had transformed into the Pure Titans), his whereabouts became unknown. Due to the influence of the Founding Titan's power used by Eren from the future, Bertolt, who had to survive, was not killed by the Titan that Dina had transformed into, which led to his mother, Carl Jaeger, being devoured by the Titan that Dina had transformed into. Eren then went to the frontier for two years, and in 848, he joined the 104th Training Corps with Mikasa and Armin. Eren graduated fifth in his class, but insisted on joining the Survey Corps.
During the defense of Trost District south of Wall Rose, after witnessing his classmate Thomas Wagner being eaten by Abnormal Titans, Eren angrily chased after the Titan. Midway, a Titan bit off his leg, causing him to crash onto a rooftop. To save Armin, Eren rose again and was eaten by the Titan in Armin's place. While inside the Titan's body, the Titan transformation ability injected into him by his father Awakening, causing him to reappear as a Titan and kill 20 Titans in succession. During the recapture of Trost District, he transformed into a Titan but went berserk. Later, at Armin's call, he regained his self-awareness and lifted a giant rock to block the city gate.
Later, he was imprisoned in an underground cell by the Military Police Brigade. Erwin, Levi, and Hange visited him one after another. During this time, Eren expressed his desire to join the Survey Corps to Erwin and Levi. Levi agreed to his request and decided to take Eren under his care. Subsequently, Eren was put under investigation. During the investigation, he faced much criticism because of his Titan identity. The Chamber of Commerce and the church planned to execute Eren on the spot, while the Military Police Brigade Commander, Nile Dok Deckard, planned to dissect Eren and make him into a specimen. Mikasa tried her best to defend Eren in court, but not only did no one believe her, but she was also questioned because of the incident when she and Eren killed the kidnappers when she was 9 years old, which led to doubts that she was one of the human-shaped Titans. Seeing this, Eren could no longer contain his anger and angrily denounced the people present as cowards. Just as things were getting heated, Levi beat Eren in front of everyone under the pretext of "teaching him a lesson." With Erwin's encouragement, President Zackly finally decided to hand Eren over to the Survey Corps, with Levi Ackerman as his guardian.
After joining the Survey Corps, Eren, Levi, Petra Lalu, and others formed Levi Squad to participate in the expedition outside the walls as bait to capture Titans. They encountered the Female Titan and wanted to transform into one to fight, but were stopped by Levi Squad. After witnessing the annihilation of Levi Squad's squad, Eren completely broke down, believing that his choice to trust his comrades had led to their deaths. In a fit of rage, he immediately transformed into a Titan and fought the Female Titan. However, upon recognizing Female Titan true form (Annie Leonard), he froze and was defeated. He was later rescued by Mikasa and Levi.
Battle of Titans
Later, together with the others, they captured the Female Titan. At first, Eren hesitated, not wanting to transform and fight her. After hearing Mikasa's reasons for fighting, he made up his mind to start the battle. In the end, he fought the Female Titan with the sole intention of killing the Titans, including Annie in her true form. However, he was stunned when he saw Annie crying, which allowed Annie to crystallize. Eren was then forcibly pulled out of the Titan's body by Levi, who arrived shortly afterward.