Searching for a manhwa title

It's a straight historical manhwa. FL has pink/purple hair and is an alchemist. ML has black hair and red eyes, he's a villain in the OG novel. Iirc, FL once trapped (?) in a tower with ML when he's still 'tame'. There's a scene where something like monster or disaster appears in a blond man's house (the good man ig?) and FL actually defeated it, but made it look like ML who did it, to gain trust from the blond man. When the ML still unconscious after the incident, FL disappeared. Sorry if this is too vague or a bit different from the actual story it's been so long since I read it