Nux and Nax were left to ”Home for troubled young” when they were too young to really remember anything about their parents, but they do faintly remember that they did have parents, not that it has any effect in their lives, as they have no interest in seeking them out. Due to being sisters, they were kept in the same room, a room that was designed for a single creature, be it with two beds. Because of this, they grew up to be very close, as they didn’t really have any other choice, being stuck so close to each other, and not really having anyone else to turn to for emotional support.

They were two of the few who the institution ended up kinda helping, as the reason for them having been brought there in the first place, was their violence towards each other; a permanent reminder of which can be seen on Nax, as one of their fights had ended with Nux biting off and eating Nax’s right ear. This however doesn’t mean their problems were solved, as while the treatments kept them off each other enough for them to start caring about each other, they now channel their worst habits towards others.

Their life in the institution didn’t have much more effect on who they ended up becoming, as their worst tendencies had always existed, and while the experimental treatments and medicine didn’t help with it, it didn’t actively make it any worse either, if you don't count growing disdain towards figures of authority. They spend most of their time together, and while they got along with some other patients, they didn't make any real friends. 

Their time in the institution ended, when a fire from unknown origin started in the basement and engulfed the building, and while they made it out alive, Nax was caught in the flames enough to be burned, leaving her with permanent scar tissue on the left side of her face, neck and shoulder. The scar tissue wasn't the worst issue of the injury however, as she also lost her left eye. It took her a while to accept her new physical appearance, but she came to embrace it, partly thanks to her sister, as Nux thinks it's cool.

They learned later that one of the other patients had apparently perished in the fire, though they didn’t know much about her beyond the fact that she was always carrying a dragon plush toy with her, a toy which she also spoke regularly to, not that it was too unusual in that place. They however came to doubt this information later in their life.
 

After Nax had gotten medical treatment for her burns and they started to heal, the two ran away from the hospital, and while they were still quite young, they managed relatively well on their own, because their biology allows them to eat things most creatures couldn’t, things that others throw into trash, and on the streets where they ended up on, there was lot of trash. Nux and Nax also were, and still are, notably smaller than other bipedal creatures of equivalent maturity, and this worked in their benefit too, as it allowed them to better stay hidden in the gang and corruption filled streets, and it also made others underestimate them, giving them the benefit of surprise.

As the years went on, the two started gaining some infamy on the streets as with their growing confidence, they started letting their worst urges free.

When it comes to the worst parts of Nux and Nax, they are different yet they complete each other. They both enjoy the pain of others, but with their own quirks, Nax is more into the psychological side, caring more about the reaction of the target than what was actually done, while Nux likes the physical side, partly because she likes to get a taste of them, literally. Because of this, they often play an act where they overplay Nux's worst habits to terrify their unfortunate target.

The two were small players in the city for a long while, known to some, but ultimately just a part of a whole messed up reality, that is, until one day someone came in and toppled the biggest gangs in the area, leaving a massive power vacuum, which the two naturally took a advantage of. They didn’t start a gang, as they had no interest in organized crime in that way, and instead, they started an operation in gaining information and then selling it forwards, weaving strings into the gangs and other forces filling the power vacuum, making them an unnoticeable yet powerful force in the whole.