Love your game, the art and animation, though I think you need to work on the Prince a little since he seems more like a Tsundere and not a cruel prince. Maybe you can have people treat him depending on how he interact with the first character he met (forgot his name). A suggestion for the slave market thing, maybe have his brother buy him and "save him", he is still royalty and the brother seems like someone who would do that, but no longer holding as much authority as he once did, some of the servants started to abuse and molest him, lets face it no matter how cruel a person is as long as his hot they will have admirer who would like a piece of them. Heck maybe some of the squire who use to work for him, and with the Price pride he would probably remain quiet.
Or you could have a romantic ending where the prince lead an army of monster to destroy the kingdom, and have revenge on those who "abandon" him and take his rightful place as a king, a puppet king for his monster husband and master but a king none the less.