One important element in Ymir's back story is her origin. She was just an ordinary girl before becoming a Titan. Then there's the fact that she was a slave, which made her vulnerable to exploitation when she got the Titan power. Also, the way her power was passed down through the Subjects of Ymir is a key part of her story.
The key element is her encounter with the tree and the spine - like thing which made her the first Titan. Another is her status as a slave which led to her being used by others for her new - found power.
Ymir was the first Titan. She was a slave in the Eldian Empire. One day, she came across a strange tree and entered a body of water there. She then merged with a spine - like organism and became the first Titan. This power was later used by the Eldians to gain dominance. But Ymir was also exploited and used for centuries.
The key elements in Ymir's back story include her emergence from the primordial state, which was a time of nothingness and potential. Her physical body being the raw material for the creation of the world, like the sky, the earth, and the seas. And finally, the act of the gods overpowering her, which is a significant part of the power dynamic in Norse mythology.
One possible fanfiction could be about their adventures together within the walls. Maybe they discover a hidden passage that could potentially change the fate of the Survey Corps. They might face Titans together and in the process, their bond deepens as they rely on each other's skills and instincts.
In a fanfic, Christa and Ymir might find a hidden place within the walls. This place has secrets about the origin of the Titans. As they explore it, they learn more about each other. Christa could discover Ymir's past and understand why she is the way she is. Their story could be filled with mystery and adventure, and in the end, they become even closer friends.
One key event was his mother's death in the Underground City. Another was when Kenny Ackerman found him and taught him to fight. And of course, his decision to leave the Underground and join the Survey Corps was a major event in his back story.
One more concept could be a time - travel fanfiction. Christa and Ymir are sent back in time to a crucial moment in the history of the walls. They then have to use their knowledge of the future to try and change things for the better. Their relationship would play a key role in how they approach this new situation and the decisions they make.
The back story of Attack on Titan involves a complex history of humanity, Titans, and the walls. It delves into the origins of the Titans, the politics and power struggles among humans, and the secrets of the world they live in.
One interesting plot could be Ymir protecting Christa in a dangerous situation within the walls. Maybe when Titans are attacking, Ymir uses her unique abilities to fend them off and keep Christa safe. Another plot could be a story about their friendship growing deeper as they face the secrets of the world together. They might discover something about the origin of Titans that changes their perspective on everything.
The plot could revolve around their friendship during a difficult time within the walls. Maybe there's a shortage of resources, and they have to work together to ensure the survival of their group. Christa uses her diplomatic skills, while Ymir uses her combat abilities. Their cooperation not only helps the group but also deepens their connection.
Ymir's character could be developed by exploring her past more deeply. For example, her time as a Titan before joining the Survey Corps. This could make her more complex as she struggles with her identity. Christa, on the other hand, might develop by breaking out of her 'nice girl' persona. As she faces more challenges with Ymir by her side, she could become stronger and more assertive.