The Dragon's Secret Name

In a world where every living being has a secret name, Kate was born with the ability to see through the magical veil that separates human and fae worlds. Not only that, her body produces too much magic, making her a target for all the creatures who want to take advantage of it. Her family always had problems with this, and they didn't think twice about selling her to the fae's great leader, the Pale King, who showed up on their doorstep and bought her and her younger sister.
For some time, Kate was used as a source of magic for the Pale King, until one day she managed to escape, alone, cursing herself for not being able to bring her sister with her. Pursued during her escape, what she didn't expect was to be saved by a great black dragon who has no wings. He fought off her pursuers and let her go.
Years later, Kate never forgot her sister or her savior. Now she acts as a mercenary, and she wants to find ways to confront the Pale King and get her sister back, even though she fears the girl won't even remember her. But she heard that a great black, wingless dragon will be put up for sale at an auction where magical creatures can be bought with their secret names written on a document of ownership.
Could he be the same dragon who saved her before? Would he help her again? She doesn't know the answers to these questions, but at this point, Kate is willing to obtain him, even if by alternative ways.