A beauty injured in the line of duty trades her remaining life for her father's as a living trophy for an ancient beast.

Allura was shot in the line of duty, and the radiation is slowly eating her cells. Her life will not be long, so she is discharged and sent home to die. Her father was off on a trading mission, and he runs afoul of a terrifying creature who straps an explosive device to his head to ensure that the merchant will send the most beautiful thing that he sees back to the beast.
Allura doesn't mind leaving home. She doesn't want to have her family watch her fall apart. She agrees to be something pretty for the monster to look at for as long as it lasts.
The creature has a plan, an agenda, and he is willing to spend the rest of Allura's life pursuing it. It is a good thing that he has the cure for her particular brand of radiation poisoning. As long as she abides by his rules, she gets the treatment, whether she knows she is being treated or not.