Yeah like how he was saying he would play any role that MC thinks would match him and how that was the only option that he was not ok with seems weird but I believe that he might not directly be the heir like he might have been but because he was only half related he was thrown to the side of the family but because the family might still find use of him they would have been looking for him but yet that would still not explain the dead body but I hope that's explained soon.
Yh I agree I imagine it being that if he was thrown out and abandoned by the royal family he hates them and the idea of being associated with them so being called or known as the prince is the last thing he wants.
Is it just me thinking he could be that prince?