I bet that Nanny is trying to curry favor the Duke because
Spoiler!
She is actually abusing that cute child.
The ghost that hugged Dive is
Spoiler!
His mother who knows about the abuse and asks Camilla to help him
Dive is so cute 
and he is
Spoiler!
He is adorable and loves Camila and King. Camila sees him as her younger brother and takes care of him. Sometimes he and Camila video chat thanks to a magical item. The Duke's dead wife, Sharua, gave Camilla her safe in gratitude for saving her son from the nanny. The safe had a lot of money and precious jewelry, although it was tempting, Camila didn’t keep it but gave it to Dive and told him that it was a gift that his mother left for him.
When Dive was around other kids he had a cold attitude, just like Camila as a child he didn’t want others to get close to him for fear of being hurt. He was educated by private tutors, so he didn't normally interact with other children. At Camila's suggestion, he started going to the academy and finally made a friend. Camila told him to introduce her to his friend next time, but he was hesitant because he doesn't want to introduce his sister to anyone because she is HIS sister.
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule
you will find me in most romantic historical manhwa comment sections 
you will find me in most romantic historical manhwa comment sections 
