The ShadowHunter by Opal Reyne

When her younger sister is stolen in the dark of night, Valerie infiltrates the northern kingdom to rescue her. Parading around as a human and hiding her Witch scent, she doesn’t realise she’s stepped onto a Dragon’s hunting ground – or that the Dragon has settled his lustful sights on her.
She only wanted to save her sister, but she can’t resist the way he sets her heart on fire.
Hiding his Dragon linage, Geryon cares little about the gala thrown to find the king a wife. It’s nothing but a means to an end – a trap. That is until a certain, cold-hearted woman enthrals him as she flits around the palace with her unfeeling grace.
As every day passes, his desire to see her fall into rapture within his arms grows stronger. He even considers keeping her.
But, their game can only last so long before they discover that neither one is who they are pretending to be. What will happen when Geryon realises the human he has been bedding is actually something in which he hates the most?