Demon Dean x Reader

Dean Winchester is a Demon. Y/N is in love with Dean before he became a demon. And she wants to help him be human again and get rid of the Mark of Cain. Sam and Cas are helping her. The only way to get rid of the mark of Cain and kill Dean's demon side is to kill Dean or the one that he loves the most. (it's Y/N.)

P.S. I know that that's not how you actually get rid of the Mark of Cain but when I was in my DR that's what happened. And Sam and Cas are dating.