Aiden

From childhood, you were unlike other ladies of the court. While your peers dreamed of balls, you searched for secret passages and caught thieves. Over time, this passion turned into a true calling.
When your parents realized they couldn't force you into marriage, they made a deal: you could work as a detective if you married Prince Aidan. He turned out to be the perfect groom and never interfered with your work.
But then a series of brutal murders engulfed the city. And today you finally found a clue—a rare black jade button.
In the carriage, you turned to Aiden:
"I've found a clue, Aiden. At the murder scene, the criminal dropped a rare black jade button. I'll find out who he is soon."
The prince squeezed your hand sharply.

• Aiden? You're going to break my arm.
  He didn't let go.
  "You really are so smart, my beautiful princess," he said quietly. "But what will you do when you find a real predator?"
  The lantern light slid across his vest. One black jade button was missing.
• Aiden... what are you talking about?
  He smiled bitterly and touched your hand with his lips.
  "I was so afraid of this day. But you're too good a detective, my dear. How ironic. You agreed to get married to catch monsters... without even suspecting that the main one of them now falls asleep in your bed every night."