This woman right here is a truly compelling character:
Krista Lenz... no, no, I should be calling her by her real name: Historia Reiss.
When we first meet Historia, she goes by the name of Krista Lenz: a pretty girl who goes around doing kind acts for everyone so that others think highly of her. Her kind act are so extreme that she's even willing to sacrifice her life in the process just to be viewed favorably. In fact, her looks and sweet-hearted nature eventually lead her to be known as a "goddess" among her peers. She seems nothing more than someone with a cute personality and appearance and that's it.
But what if I told you she was an illegitimate child and did all those kind acts to boost her self-esteem and win the hearts of those around her because her background made her believe she was nothing more than a mistake who should never have been born? Well, that's exactly who Historia is.
Historia is an illegitimate child that was born out of an affair between the King of the Walls and a servant to the royal family. Yep, she's royalty, but being born from a mistress is a big no-no in the walled society,
especially when she was born out of the King's secret affair. Because of her status, she and her mother were forced to live on an estate owned and administered by the royal family. Her life during that time was very cruel. Her mother never spoke to her, and the local kids bullied her when she tried to leave the estate grounds on several occasions. She was so isolated that she could only make friends with the farm animals she cared for. Historia even tried to hug her own mother when she started reading books and learning what a true mother and daughter relationship is like, but her mother violently slapped her and lamented, "If only I had the courage to kill when you were born." Historia was happy because it was the first time her mother spoke to her, but it was from that experience she learned about how she was a burden to the royal family.
There was a woman that frequently visited Historia, and her name was Frieda Reiss. Historia did not learn this until much later, but Frieda is her half-sister (Prior to learning that, she viewed Frieda as an older sister figure). Frieda taught Historia how to read, and she encouraged her to become a kind-girl that everyone would love. It was thanks to Frieda that Historia used that "goddess" persona for most of her life later on.
Life took a dramatic turn, however, when Historia and her mother were being escorted by the king to the Reiss (the royal family) household so that Historia would finally be recognized into the royal family. On the way, they were stopped by the Inner Brigade of the Military Police, who were tasked to kill Historia and her mother. Her mother was the first to die, with her final words being a wish that Historia was never born. As Historia was about to die, her father saved her life by removing her from the Reiss household and giving her a new name: Krista Lenz. From there, she would be enlisted to the army with the hopes of putting her in the Survey Corps so that she would likely be killed off by a Titan.
During her years in the military school and most of her Survey Corps career, Krista played the role of a "goddess," doing kind acts so that others would think highly of her, and Krista felt the need to be recognized as a kind person because the fact she was an illegitimate child and thus was seen as a burden for most of her life affected how she saw yourself. This would start to change when she met Ymir, a fellow soldier. Ymir knew about Historia's origins, and she convinced her to quit playing the role of "goddess" because it lead to her demise. Moreover, Ymir encouraged Historia to start believing in herself and "live with [her] head held high." Basically, the message is that she should stop worrying about what others think of her and live life the way she wants to without any stigma holding her down.
This panel sums up Ymir's teachings to Historia pretty well:
This is among the lessons that Historia learns, and it will factor into the culmination of her character development later on.
Ymir and Historia ultimately fall in love, but Ymir eventually escapes with Reiner and Bertolt. It is around this point Krista reverts back to her original name: Historia Reiss. However, Historia became a shattered individual.
Historia goes as far as saying her real personality is one who is empty inside. Eren catches on to this and tells her that she finally become a normal and "less creepy" person at that moment. He says:
Historia shrugs off Eren's comment and continues to think of herself as someone who is vacant with not true identity. This changes once she and Eren are captured by the Inner Brigade of the Military Police and eventually reunites with her dad, where she is forced to undergo a ritual where she will turn into a Titan and eat Eren, who is chained up, in order to become a Titan Shifter and regain the Founding Titan power for the Reiss. Initially, Historia buys into her dad's goals, mainly because her dad tried to convince her to do the job by using fatherly language.
One of the Inner Brigade members of the MP tries to convince her that her dad is only using her and doesn't actually love her. An emotionally shattered Eren even convinces Historia to eat him to save humanity, and at the moment, Historia feels grateful for Eren, remembering when he called her a "normal" person. She hesitates on injecting herself with the Titan Serum, and her dad intervenes yet again, this time trying to convince her that she will become "god" if she takes back the Founding Titan. Upon hearing "god," it is at that moment Historia remembers everything that Ymir told her: stop letting stigmas or other people's judgment dictate how she should live her life, but live it for herself.
It is at that moment we have one of the best scenes in AoT:
Now THAT is how you retaliate against someone who is using you!
She then runs over to Eren and starts to free from the shackles. Still shattered and sobbing, Eren continues to beg Historia to eat him, but Historia knocks some sense into him by lying to him that she is mankind's enemies and wants humanity to be wiped. Again, she isn't being serious about the enemy part and is only saying that just to get Eren to gain some motivation on life. She then tells him that she is doing this because she's his friend; thus, she can't let Eren curse himself to the point he wants death. Through this entire scene, we see how Historia's character development truly shines, and it only gets better.
Her father licks the Titan Serum and turns into a Pure Titan, which eventually leads to the Survey Corps and the nearby Garrison having to kill the Titan before it reaches the nearby district. Historia is initially ordered to stay down during the oncoming battle, but she decides to fight anyway. Levi questions her why is she doing so, and Historia tells Levi that it was him that convinced her to choose between stand by and eventually die or fight to live. Back when Levi first ordered her to become the queen, Historia refused (because she felt as if she had no identity and thus no reason to become queen), and he had to grab her to forcefully make her comply with becoming queen. Now, she makes the decision to take the position on her own accord. She has started to believe in herself and develops her own strength.
Historia is also the one to land the killing blow on her dad, and when she is asked by the townspeople if she is the one who killed the Titan, she proudly proclaims her true name and states she is the true ruler of the walls.
She is eventually crowned as queen of the walls, and she follows another character's idea of punching Levi when given the chance. Previously, her Krista persona would've prevented her from doing so because she would think punching someone would lead to others thinking badly of her and thus adding her to burden of letting the illegitimate child stigma get to her, but now, Historia does not care what Levi will think and does so anyway, not worrying what others think of her.
If you read through all of this, you should have a good idea how wonderfully written Historia is. She is an illegitimate child to the royal family who initially does kind acts just so others think well for her due to her taboo background, but overtime, she learns to not let others dictate how her life should be like and instead live life the way she wants to. Historia is without a doubt one of my top favorite AoT characters because of how amazing her character development is.
And now, she has become the queen of the walled society, and a much stronger person overall. You go, Queen Historia!