Responses
But, he IS the crown prince's son, though. It's just that he's illegitimate (born out of wedlock), so he's in danger because he's in a similar situation to the one the ML was in, as a child: his father's family thinks of him as a mark of shame, so they'll keep trying to make him disappear, unless they become sure that they can't produce a legitimate son (born of the legal wife)
Ohhh for some reason, maybe my memory or the translation, but I thought the little boy was the princes son but it's his brother.