Annie Leonhart

Annie Leonhardt is a member of the 104th Trainees Squad

History
Annie had trained with her father ever since she was young. From the Trost District in Wall Rose, she is considered a solitary, stoic type and close friendships don't come easily. During a flashback in Ch.33, her father begs for forgiveness for the way he trained her. Thinking it may be too late, he tells Annie to treat everyone as her enemy and she promises to come home to him.

Story
Graduating 4th, a rank below Bertholdt Fubar, Annie choose to enlist in the Military Police. When the Colossal Titan breached Wall Rose, the same way it did with Wall Maria, Annie was assigned to rear guard with Mikasa and a few of the others to help fend off the Titans as the people are evacuated to the safety of Wall Shina. She was involved in helping Jean Kirschtein and the other retake the supply unit to restock the gas canisters for their gear. While watching Titan Eren fight off the other titans, Annie overhears Jean and Reiner arguing and so she think that he may be their ally. She learns about Eren's shapeshifting ability.

In Ch.17 during hand-to-hand combat training, Annie easily bests Eren and Reiner with a kicking technique her father taught her. Later on during dinner, she watched as he used the same technique to subdue Jean when he tried to pick a fight again. The next day, Annie and Eren were watching him as he practice hand-to-hand combat. She noticed that Jean's only taking it seriously just to pick a fight again and doesn't see anything positive from it. Annie points out something wrong in how Eren handled the kicking technique and offers to teach him the proper techniques.



Soon the two titans captured for research are killed and the Military Police check the Three Dimensional Maneuver Gears from the trainees. During that time, Armin, Annie and Conny Springer discussed which military branch they want to join. When Annie reveals that she will go to the military police, Conny considers joining them too and asks for her opinion. Annie responds telling him that it's his decision to make, not hers; but when she learns he'll join the Scouting Legion, she asks Armin what he would do if he was ordered to die. He tells her if the reasons are good, then he'll do so. Annie thinks he's weak physically, but yet he's very strong at heart. We later learn that she offered Marco Bodt's 3DMG for inspection as her own, and that prompted Armin to become suspicious of her. Ultimately during the Scouting Legion draft, Annie leaves to join the military police.

Arc 2: Annie VS Mikasa.
In Chapter 31, Annie awakens in her room in the Stohess District of Wall Shina. Her hair is the same as the Female Titan's when not tied up in a bun. Annie is teased by Hitch and Marlo, but a member tells them to leave her alone believing that she hasn't recovered from battle and is the only one who has real combat experience. Soon Armin approaches her and asks for help in hiding Eren until they can convince the king to better protect the walls. Annie reluctantly agrees by putting on her father's ring and escorts them to a place where they can hide. When Eren and Armin try to get her to go down an underground passageway with them, she refuses and suspects something is awry. Mikasa, having enough of Annie's games, takes off her hood and draws out her 3DMG. She refers to her as the female type titan. Armin's suspicion is confirmed when she smiles in the same way as the female titan, and by her refusal to enter the passage, where she cannot transform.

In Ch.32, after firing a signal, disguised recon corps comes out of their hiding places and try to restrain Annie. Seeming captured, she is still able with a flick of her thumb to open a small blade hidden in her father's ring and prick herself, thereby allowing her to transform into her titan form and kill those restraining her. Now, resuming her attempts to capture Eren, Armin and Mikasa realizes how desperate she is and try to get him to fight her. Overcoming his initial shock at the identity of the female titan, he transforms into his titan form and takes Annie on.



In Ch.33, As Eren tries to hold Annie off from escaping, Mikasa realises that she may be the only one who can stop her. Knowing that she may try to climb the wall to get out of Wall Shina, she trails Annie. Annie decides to fight and defeat Eren again. After that, she continues to try and escape. However, by that time, Mikasa had already caught up to her climbing the wall. Not hesitating in the slightest, she cuts off all of Titan Annie's fingers, leaving her struggling to hold on. Mikasa then tells her to fall down and pushes her off via the head. Eren in his titan form hold down the body as both the military police and the members of the Scouting Legion, cut into the flesh and try to extract Annie.

In Ch.34, Annie is trapped inside a crystal, while one of the Scouting Legion members tries to break the crystal to extract her, but Hanji stops him and tells both the Military Police and the rest of the Scouting Legion to take her underground and detain her. Meanwhile, Jean who went into the town supposedly posing as Eren learns the truth about Annie being the female titan.

Abilities:
Annie is one of the strongest fighters alongside Mikasa and Eren. She learned her techniques when she was a child and her father trained her relentlessly. One such move was a kicking technique that she used to defeat Eren and Reiner during training. She would later teach the move to Eren when she tells him about what he did wrong and how he didn't need to hold back.

Titan Shifting
Like Eren, Annie displays an ability to transform into a 15 meter titan. She uses this form to wipe out military formations the Scouting Legion uses during their attempt to retake Wall Maria. Annie's titan form is similar to Eren's form, but more feminine and muscular.

It is a mystery how Annie actually managed to know the secrets of transforming into a titan. She is more adept in using her titan form than Eren. In her titan form she is able to selectively regenerate certain parts quickly as opposed to automatic simultaneous regeneration of all the damaged parts. She is able selectively harden parts of her skin to protect it from damage or to enhance attack. Annie is desperate to kidnap Eren and reasons for that remains unknown.

Trivia

 * In episode 2 of the anime, you could spot Annie in front of the line to receive her bread rations. A scene not in the manga.