Éminence Grise Female Lead Is Trying to Make Me Her Stepmom is a Manga/Manhwa/Manhua in english language, Korean series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

I have transported as civilian 1 into the "tragic novel" I wrote with my friends for fun. Since he declares revolution in order to change his daughter's unhappy future. If I leave it like this then many lives are in danger.
"I will protect the female lead!"
That's how I started to live with the daughter stupid duke.
But the small female lead is a bit strange for some reason.


*Note: An éminence grise or grey eminence is a powerful decision-maker or adviser who operates "behind the scenes", or in a non-public or unofficial capacity. This phrase originally referred to François Leclerc du Tremblay, the right-hand man of Cardinal Richelieu.