Annie has blue eyes and keeps her blonde hair tied back in a bun for the most part, wearing her bangs over her right eye. Usually she has a cold and unemotional look on her face, regardless of her mood.
Minus the blazer, she wears the same uniform as every female character in the series, with a blue bow, white shirt, and blue skirt. However, she also wears a sweater vest with this and white indoor shoes with white socks.
During the dodgeball game, Annie is shown to be wearing dark blue tracksuit with her given name on the front of it. As the rest of her team, she is also wearing a yellow ribbon in her hair. Later, Annie changes her clothing during the Sports Day, where she is wearing a cheerleading uniform. Annie changes her clothing once again during the summer festival. For this occasion, she is wearing a light violet yukata with green and yellow circles on it.
Annie is distant around most people and rather shy when met with unfamiliar things. She is quiet with a hard exterior, however, can soften up on occasions to certain people and things.
She is embarrassed to admit that she also likes cheeseburgers which happens to be Eren's favorite lunch, too. But as soon as Eren apologizes, Annie softens up, much to Mikasa's irritation. Sooner in the episodes, she is revealed to be a Titan speaker.
Annie introduces herself on the first day of school, stating that she came from Wall Maria South Elementary School. Afterward, she and the others are called to the courtyard for the opening ceremony.
Annie is unable to confess her love for cheeseburgers because of the derision caused by Eren in the opening ceremony. Within her wrath, she threatens to defeat Eren in the tournament of dodgeball the next day. Annie participates in her school dodgeball tournament. Her team is on a winning streak until they are confronted by Eren's team. Mikasa ends up saving Eren by catching and throwing back Annie's balls, and Annie does the same. As Eren asks her about her grudge against him, Annie admits about liking the same lunch as he did. Eren apologizes and they both become friends. By the end of the game, Annie's team loses the match because Conny throws a ball at her which she forgets to dodge. Later, Annie joins Eren, Mikasa, and Armin for lunch. She offers Eren a cheeseburger steak after he drops his on the floor.
After Jean receives a love letter, an uneased Annie wishes to speak to him. However Mikasa was here as well, so the two girls begin a cold argument. Jean, assuming they were fighting for him, tried to separate them but in response the two girls hit him. In the process, Annie lets down a letter similar to the one Jean got earlier. She hits him again, gets her letter back and avoids eye contact with Jean for the rest of the day. After the end of classes, she puts another letter in Jean's locker but is spotted by her classmates and runs away. After having read the letter, Jean runs to the park and Annie appears, asking Eren and the others' advice about that letter. Later on, she meets Jean at the park. Annoyed by Jean, who was still assuming she had feelings for him, Annie hits him before explaining she wrote the letters for a friend of her. Annie then decides to call her and sharply screams. A Titan then appears and Annie explains to her surprised classmates that she learned Titan language. She then explains how did the Peering Titan met Jean. Annie adds that the Peering Titan is very shy and would like Jean to go out with her. After Jean rejected her and the Peering Titan ran away, Annie states that her friend said she would not give up.
A few years back, a younger Annie, Reiner, and Bertholdt are at a summer festival. Annie and Reiner watch Bertholdt die-cutting and complement his skill. Annie is asked by Bertholdt to go to the summer festival. Uninterested, she first refuses but eventually accepts upon her classmates' enthusiasm. The night of the festival, Annie arrives and wears a yukata. Christa compliments her on her outfit and Annie states it is a gift from her father.
At a shooting game stall, Mikasa easily wins at the game from her first try, and chooses to gift Eren her prize. Seeing this, a determined Annie tries the game and wins on her first try as well. Looking back at Mikasa, a sense of rivalry sparks and they both demand the stall owner to give them another try, with them winning every prize in the stall. When a shaved ice cup "accidentally" flies towards Annie, Bertholdt yells for her to watch out, and then protects her as the ice is spilled on him instead. When Bertholdt goes to wash up on his own and everyone starts looking for him, Annie finds him at the die-cutting table.
Annie says he had always liked die-cutting, so she had a hunch he would be there, to his amazement that she remembered. She says she has not been to a summer festival in a long time, and Bertholdt apologizes for asking her to come along suddenly, and hopes she is having fun, with her saying she does not like crowded places, making Bertholdt apologize again earnestly.
However, Annie tells him that it might have been good he asked her to come along, but says it is not because she wanted to come with him, rather she feels at ease with him and can be herself, saying he is convenient to have around. Bertholdt tells her that does not even sound like a friend, with her realizing it does sound weird, telling him maybe he is like "air" to her, shocking him even more. Annie starts laughing, then apologizes, and they both speak at the same time, interrupting each other. The others hiding behind bushes watch eagerly as Bertholdt asks Annie to do die-cutting with him. Back at the die-cutting table, Annie participates with the others and then watches as more festival fireworks are set into the sky.
In the school's 104th festival, Annie and Hitch visit the cat café. When Hitch tries to get a cat's attention, it ignores her and lies on Annie's lap.
Eren and the others head to the Titans' building to retrieve their stolen chee-burgs. In the principal's office, the others distract Titans as Eren tries to pull a key. When a Titan lunges at Jean, a scream is heard and Annie appears with her Titan friend, landing on the lunging Titan and saving Jean. She watches as Eren carries the key and slowly walks to the door. As one last Titan stands in Eren's way, Annie's Titan friend throws Jean at it, knocking it down.
- Eren Jaeger - After everyone started making fun of Eren for his love of cheeseburgers, Annie became too embarrassed about it to admit that it was her favorite food, too. For this, she hated Eren. But Eren soon apologizes for putting her in such a position, Annie begins to warm up to him, much to the annoyance of Mikasa.
- Mikasa Ackermann - Following Annie and Eren's reconciliation, Mikasa soon behaves coldly towards Annie and vice-versa, sparking up a rivalry between them.
- Peering Titan - Annie and the Peering Titan see each other as friends as they take the same Titan language class.
- Hitch Dreyse - Hitch and Annie go to the same club.
- Marlo Freudenberg - Annie and Marlo are clubmates along with Hitch.