Can somebody please spoil me about the silver haired marquis?

Figured it was pretty obvious after they stated the hydrangeas require tons of water to flourish and so does that demon plant…so yeah that ‘tool shed’ probably ain’t not tool shed, and that new silver haired bastard is the one growing it. Oh and that purple eyed short black haired character is probably his subordinate, and he’s trying to get on Bell’s good side or close enough to drug her bc he knows her and the crown prince are in a situation ship. Black haired girl saw them.