Personality:
Whether it's the taint in her blood or the shadows cast by her past, Jörmingandr is inherently selfish. She has very little qualms about leaving others to save herself, especially if she's not getting paid to protect anyone. She's double crossed and sold people out when needed, not to mention that she doesn't mind lining her pockets if given the chance, even if the contents with which they are lined didn't originally belong to her.
Other than that it'd be easy to call her quiet and cold, aloof. This is the side that most people see, since being what she is and living the kind of life she does, you don't make many close friends and it's harder to make a slip of the tongue if you're silent. For those who do actually know her she does get more talkative, though her mannerism can be a bit blunt, bordering on rude. And while most wouldn't trust her further than they could throw her, she has her own sense of morals and loyalty. Honour, of a sort. If she considers herself to be indebted, she will eventually repay it, assuming the opportunity arises. For those she trusts, she'd walk through fire, though they might not be aware of it until such a need arises.
For the most part she's not particularly given to cruelty, but there is a certain amount of blood lust shown at times. Particularly when she is vindictive or vengeful. It is at these times she can be seen to take great pleasure in the suffering of others, be it emotional or physical. Some say this is her true nature, the evil of demons thinly veiled by human blood and a conscious effort to blend in. She neither confirms nor denies it, people usually have their mind made up already. Expending energy trying to convince those who are set on ostracising has never given her anything of worth.

History:
Though she had a different name once, she cast it aside at some point and because she was born with demonic taint in her blood, Jörmingandr has always been met with suspicion and sometimes even outright hatred; discrimination something she got used to at an early age. She never knew her father, though it's likely her demonic blood came from his side. Her physical features would almost allow her to pass fully as a human, if it weren't for the luminescent odd eyes that give off a bright red and yellow colour and the greyish tint to her skin. Even so, those giveaways were big enough that talk was already going around during her childhood.
Other kids would gang up and throw rocks and beat her and the grownups would whisper ominously. So, one day she was dragged out of her house along with her mother, who screamed, kicked and fought. They were dragged to the center of the village. Both were beaten bloody and accused for every misfortune ever to happen to the village. Punch and kick after punch and kick her mother proclaimed their innocence. When it turned out beating them wouldn't be enough it was decided that harsher methods would need to be used. Waterboarding, hot embers and other means of torture were employed and eventually the voice which had proclaimed innocence turned into begging and then, at long last, admitting to anything and everything they threw at them.
Her mother was sentenced to being burned at the stake, while the little girl was forced to watch and listen. Moments of eternity forever imprinted into her memory.

By every right she ought to have died then and there, but some people seem to have a knack for surviving, and she is counted amongst those. She doesn't care to remember a whole lot of the years that followed, but she learned how to steal and kill at will. If most people already saw a demon when they looked at her then she might as well give them what they expected. It was difficult at first. She thought she might break both physically and mentally, but every time she thought she had met her limits, it turned out she could take just a little bit more, stretching and adapting to life around her.
Though she eventually got a reputation for being somewhat ruthless, she never once abused anyone who treated her with a semblance of kindness or even respect. It just so happened that those people were few and far between. One of the people who did was a young thief. She never caught his name, but at one point when she was hiding from a gang whose leader she'd scammed he fed them some false information, throwing them off. To her mind, he had no reason to do so, if anything she'd have expected him to turn her in simply because of her lineage. She wasn't in a position to chat at that point in time and slipped out of town shortly after, but she memorized his face.

These days, she has enough confidence and strength that people tend not to mess with her. In fact, she even has people approach her with work they want done, even if it's on the supposedly wrong side of the law most of the time. For some reason her looks do not seem to attract the type of people who run a legitimate business. Still, coin is coin and usually the people on the receiving end are just as crooked as her employers.