The individual ranked 4th among their classmates during training. They were taught hand-to-hand combat by their father. This person tends to be reserved and may struggle with forming close relationships. Their motivation for joining the Military Police was simply to ensure their survival.
Annie is a Titan-shifter, and as such, it was revealed that she is the Female Titan who killed most of the Scouting Legion members during their 57th expedition. Annie was part of a group of Titan-shifters that initially aimed to wipe out the humans inhabiting the walls until the revelation of Erens capability to transform into a Titan forced them to change their plans on capturing him instead. She is also the culprit behind the killings of the two captive Titans that Hange was researching.
Mikasa and Eren manage to stop her from escaping, and when the soldiers tried to bring her out of her Titan form, reminded of her father, she wrapped herself inside a hard crystal thus making the soldiers unable to obtain any information from her.Though she is affiliated with Bertolt and Reiner, she tends to isolate herself from her fellow Titan-shifters.
20 (after time skip)
As the Female Titan, she had attempted to kidnap Eren on numerous occasions, with the two even engaging in hand-to-hand combat in their Titan forms. She aims to capture Eren with the supposed goal of bringing him "somewhere." When she was suspected by Armin to be the Female Titan, the Scouting Legion had set up a trap to capture and interrogate her, though she was able to see through their plot which resulted in her attempting to escape.
Despite her callousness and brutality in physical combat, she has shown genuine concern and respect towards her past classmates, notably Eren and Armin. Despite her seeming disinterest toward her own combat skills, Eren has deduced that she has a great fondness for it, as evidenced by her showing interest in further teaching him her techniques. As the Female Titan, she has the unique ability to generate a hard crystalline substance to protect/cover specific parts of her body.