Keia was abandoned as a newborn and taken in by a woman named Ariadne when she found them floating down a stream at the edge of her village. Despite not being the same species or looking the same at all, Ariadne raised Keia as if they were her own. However, Keia always stood out in the village because of their appearance and the way they had shown up there. Many believed they were some sort of bad omen or a sort of demon child sent to punish the villagers for their sins. Keia wanted to fit in and be like other kids of their age and so they tried changing themself in any way they could -- covering up their "stripes", trying to get rid of their horns, dyeing their hair etc. However they were still bullied and treated differently by pretty much everyone except Ariadne and given quite the hefty heap of trauma because of who they were -- something they couldn't change no matter how hard they tried.
Eventually after Ariadne died from an infection (which no one wanted to come and help cure because she was associated with Keia), Keia left their town. They had gone to Ariadne's mother for help as a last resort but no good had come from it, and Ariadne died later that night with no one except Keia to hold her. After the ruckus Keia had caused with Ariadne's mother, the villagers decided it was time to get rid of Keia for good, and so the following morning at dawn, they set their house on fire. With Ariadne dead, Keia no longer had any willpower to fight the villagers' onslaught, but they were saved from the house by a girl named Heidi, who had other plans. At the age of 15, Keia left their childhood village, and the memories from it eventually turned into voices in their head that stuck with them persistently throughout the rest of their life.
Keia's favourite dish is any kind of pasta with tomato sauce on it. They are very much interested in learning about humans. Sometimes they go to the nearest human-populated town/city and just watch people. What a creep
Heidi, the girl who saved Keia from the fire, was the only other person Keia had ever seen who looked like them. After getting over their resentment towards her for not only saving their life but also just being better than them in every possible way, the two of them got to know each other better. They had actually met once before, a week or two before the fire, when Heidi was hunting on the outskirts of the village. This time around, with Keia no longer tied to any particular place or person, Heidi revealed that she was sent to recruit them to the organization she worked for. Actually, she was sent to the general area of Keia's village to recruit anyone deemed suitable for the cause, and Keia happened to fit the criteria and be extra influenceable due to their vulnerability. Heidi brought Keia back to the organization she worked for, leaving out an important detail -- it was one of the most infamous terrorist groups of the region. However, the organization promised Keia a home, a bed, and a community in exchange for their unwavering loyalty, and with nothing else to live for, Keia agreed, not knowing the cost of said loyalty. Note that the voices in their head followed them everywhere they went, and worsened once they started getting involved with this group.
Over time and once assimilated into the organization, Keia became pretty much indifferent to anyone except for themself -- a result of the way they were treated as a child, and the brutal nature of the terrorist group. They didn't believe that it was worth caring about anyone except for themself because in their experience, they had always been let down. Even after meeting Heidi and others who could have been promising friends, Keia still kept them at an arm's length. This was perfect for the terrorist group however, as it allowed them to give Keia the most upsetting of tasks and they wouldn't even bat an eye.
CW: violence
The group had a sort of "initiation" in which a member wanting to rise into the higher ranks had to prove themselves (recruiting Keia was Heidi's initiation). Partly fueled by this and partly by the voices in their head getting uncomfortably loud, Keia went back to their old village and massacred every single man, woman, and child who lived there, finally getting revenge on the people who had shunned them their entire life and allowed the only person they loved to die. They burned the entire thing down once they were done, also in an attempt to satiate the voices in their head. (They only got louder lmao) The group approved of this demonstration of Keia's ability and granted them a special rank. Now among the most highly ranked, Keia would go on to be given the assignment that would tie their and Cassius' stories together.
The voices in Keia's head are basically symbolic of the people whose lives they're responsible for ending (directly or indirectly) and how they deep down feel guilty - or at least unsettled - about it, even though they put on this cold, indifferent front.
At the age of 19, Keia as well as some other, lower group members accidentally hit Nathaniel and two of his family members with their truck, taking the life of his mother and sister. Keia was not driving, but was supposed to be supervising/directing the one who was, and ensuring a smooth escape from the job they had just completed. Because of this accident and leaving behind Nathaniel, a survivor (and therefore witness), authorities were able to track down the truck and link it to the terrorist group's base. Although they managed to escape before the authorities arrived, Keia was held accountable by the group leaders for the messy completion of the job and the subsequent (temporary) disbanding of the group. The world is told that the members of the group are dead, even though no bodies were found. The memory of the car crash haunts Nathaniel for years after, along with the flash of red hair he saw through the window of the truck moments before they collided.
Nobody knows who Keia's parents were, and Keia has never had access to any resources that would allow them to find out. However, there are rumours that Ellison Flores had a secret, non-human lover in his youth, and since Keia is thoroughtly associated with fire, if these rumours are true, it is possible that Keia is related to the Flores family. Fire still burns Keia and they cannot consciously control it, but when they are around it with strong emotions, it burns a bright red colour and seems to bend to their will, becoming more dangerous to those around them.