Responses
This evidence sounds very convincing I agree.
I think the Duke used the drug on Louis when they had a drink together and the Duke confessed, only Louis left and ran into the Prince as the drugs hit him, so the Prince took him to bed. That’s my prediction at least.
Speculation about the duke being a serial killer might be true since all evidence point towards him such as all victim that have the same feature as Louis and also about the white kill drugs, he might be using it on Louis also 4 months ago during the ball but i’m sure the duke ain’t the one that rape him (the prince might be the one who helped him during that critical time i guess)