Aberrant behavior masquerading as love

Exploration Stage: Feast Garden
From: Huntress
Description: It seems the relationship between the father, Douglas, and his daughter was not as good as he made it out to be. Oh, by the way, I found a rather odd hairpin in Mirelle's hair... I think it fell into the grass during the commotion earlier. Can you look for it?
Completed: I knew I was right. This is a spy hairpin. Look, look at the stone here. It's so he can keep an eye on her. If Douglas gave this to his daughter, he may have been watching her the whole time. I'd like to know what other secrets he's hiding and how they relate to this case.