Him and that girl, forgot her name, will make it seem like elsen run away with Erita and betrayed the prince when in reality it was all planned by them so that the Prince could ask for Elsen to be killed on the spot when found.
In order for Luce to stop his madness, he will give himself up to the Prince, it was like a trade where he sleeps with the Prince so that the Prince will go back on his word and not kill Elsen.
And this is what the Prince wanted because after he sleeps with him, he will make Luce his concubine, strip him from his position and lock him up like his property.
I will say no more.... but things will get worse and then better, then worse again, then finally better in the end