(subject to tweaking still)
Eighteen years ago, a merchant traveling through the ??? mountains happened upon the most beautiful woman he had ever seen, saying her donkey had dropped dead by the side of the road. He offered her a ride, she accepted, and before long they were spending the night together. Afterwards, though, something terrible happened: she was suddenly an eight foot tall monstrosity. He had a sudden and horrified recollection of scoffing at his grandmother's warnings about foul beasts disguising themselves as beautiful maidens as she mauled him. Nine months later, a group of travelers woke up to find a newborn baby girl in a basket next to their fire. With no idea where she had come from, some of them advocated leaving her for the elements. Luckily for the infant girl, though, Thorzen Marilis, a farmer from the outskirts of Zann on the way back from visiting his sister in Kazdan, couldn't bear to leave her, and took her back with him as his own.
Kyra grew up as something of an outsider, always alone and quick to anger, made fun of by her siblings and the other kids for her overly pale skin and her mismatched eyes. Though her parents insisted that yes, she was absolutely their daughter, she had doubts: she didn't even look anything like them. It only got worse when, as she got older, her fingernails started growing longer and harder no matter how often she cut them.
When she was thirteen, the mysterious dreams started. The dreams seemed to be telling her that she should go to the mountains; though it was a deep, primal longing, it scared her and she resisted. Eventually, she confided these feeling to her father, and he told her the truth about her past. She ran out of the house, upset, and into her brother Rauno (six months older than her, which she suddenly realized should have been a dead giveaway – how had she been so stupid?). He said "what's wrong with you, ghostie?" and she snapped at him, slashing at his face and cutting deep into his eye.
She stood there dumbstruck for a moment, but once what she'd done hit her, she ran off towards the city, not looking back. She ended up in the vast patchwork of the Quilt, found shelter in a little nook between two tents, and slept. She tried to make it on the street, but she had a hard time: she just didn't have the knack for being a good beggar, and really, really didn't want to steal or turn to prostitution (though her exotic appearance got her some offers). She tried going to the guards and to orphanages but was turned away as too old; she tried getting jobs but was turned away as too young, too strange, too mysterious.
She managed to survive off of scavenged scraps and the occasional bit of charity from a church for a few weeks, but she knew that couldn't last, and in desperation she turned to outright theft. Feeling awful about it, she cut a few purses and managed for a time. More than anything, she felt a longing to seek out the mountains, but somehow she knew if she went that it wouldn't turn out well.
One day, she tried to cut the wallet off an old man walking down the street who looked well-off and inattentive. As soon as she did, though, a magical alarm blared, and the man turned and cast some spell that dazed her. The man took pity on her, asked her story rather than calling the guards, and eventually offered to take her in as an apprentice mage in his shop. Not having a better option, she tried, but just didn't have the aptitude for it at all. The old man took a shine to her, though, and kept her around as a nonmagical shop assistant anyway.
Over the next few months, the longings for the mountains got worse, and so did her outbursts. The mage finally sat her down one day and suggested the monastery out in the farmlands. She had never heard of the place, but he thought that although she was older than their usual students, they might help her learn to subdue her mysterious longings, and her natural talents might be a better fit for their way of life anyway. He eventually convinced her that it was a good idea, and took her to the monastery.
It turned out to be a perfect fit. The meditation and mental exercises did help her learn to keep her longings and her temper in check, and she loved the physical training. She still had no idea what she was, why she had these claw-like nails or why her skin seemed tougher than everyone else's, and what the longings were about, but she managed to kind of stop worrying about it.
After a few years there, when she was seventeen, the monks told Marilis it was time to go out in the world and test her abilities. She returned to see her old friend the mage before figuring out what she would do, and he had somehow fallen in with an investigator from Kazdan. She was a little skeptical of this outsider, but worried about this old man who had saved her life and didn't want him getting hurt, so she went along with them.