Ascian grew up in a human farming village in the countryside surrounding Falcon's Hollow and lived a normal life until she was 10. On her birthday, she became very sick and was bedridden with a rash that covered her entire body.
It quickly became obvious to her family that this was not a normal disease, and they asked the village wiseman to examine her. The folk remedies he used seemed to help, but her skin remained a dark red even as the sores and irritation receded.
It was then that the rest of her devilish heritage revealed itself. Her eyes changed, fiendish horns pushed their way out of her forehead, and she even grew a tail.
Shocked and frightened, her village drove her out into the wilderness, alone. Ascian would surely have died there, had she not been found by a traveling gnome wizard.
Unafraid of her infernal appearance, he took her in and cared for her as his own child. He taught her magic, self-defense, and some of the nature of her existence. Ascian became obsessed with learning more about tieflings, demons, devils, and the Hells. Having exhausted her benefactor's library, this search for knowledge often led her to the hidden and dangerous parts of the world, including the Darklands.
Ascian's treatment at the hands of her home village and her experiences since then have made her distrustful of most folk, but particularly humans. Her social isolation during her formative years and "evil" appearance make it difficult for her to relate to others and read social cues. She's also impulsive and unlikely to spend long considering the consequences of her actions.
Conversely, she's nimble-fingered and quick-witted, which means she often outmaneuvers her opponents both on and off the battlefield.
As you might expect, Ascian hates to see others bullied and mistreated for things that have nothing to do with who they are as a person. That combined with her impulsiveness has gotten her into more than a few scrapes but it's also built her a reputation as someone who can be counted on to do the right thing.
When it comes to other tieflings, she has a neutral attitude. Many are just trying to get on with their lives while others live down to the demonic expectation that society forces on them, but Ascian tries to be open-minded when meeting her fellows for the first time.