Responses
All royal children have the right to inherit the throne, even if a crown prince has already been placed. Most of the time people get rid of the other royal children so only one person is alive. The duke mentioned how those around the other royals have died, defected or disappeared which shows that something dirty is going on in the background
recent chapter made some things clear. she is sent to the palace to be a nursemaid for the prince: so this means the prince is just a kid. and obviously somebody is after the kid's life since he was poisoned and all the other people they sent before all died too.
the bitchy maids mentioned that they were in the abandoned palace, so his mom may have done something to warrant that (or maybe sent there to pretend to fall out of favor). my guess is that the prince's mom is already dead. so why are people after the prince's life? is he the crown prince? or the child of the empress? or some half blood?