I Took the Male Lead’s Place and Became the Duke of the North

I thought I had possessed the body of a nameless extra in a dark, tragic novel.
“You said you have no name? Then I shall give you one, as family. ‘Eloise.’ How does that sound?”
…Until I realized I was that “Eloise” — the one mu*dered by the psychopathic male lead.To survive, I must rehabilitate the male lead and grow stronger myself..
.
.
“Master.”
“S-stop! Don’t call me that!”
But somehow… I ended up taking the male lead’s position as the Duke of the North.
And the male lead, now turned into a s*ave, says—
“El, I remember the day you reached out your hand to me. I’ll never let go of that hand I held back then. Never, for the rest of my life.”
Now he’s obsessed—not with the original heroine, but with me. How did things end up like this?!