Thankfully, the kid wasn't behind the actions of his mother & knew nothing of them. He's clueless and had a mad crush on the protagonist. As such, he fears for her life & wants her to come back safe, but simultaneously doesn't know the extent of his mother's/family's cruelty.
What will he say after the big reveal and what will the Emperor do once he determines that the son is innocent (albeit a love rival) and has been protecting the MC in what ways that he can?