Dean and Cas have been dating for a while now, secretly, but what will happen when Cas' mom and Dean's dad gets married and they become stepbrothers?

THIS IS NOT MY BOOK!!! I HAVE NOTHING TO DO WITH THIS BOOK!!!! The original book Twist and Shout by the author from achiveofourown (Gabriel (AO3)) ALL THE CREDITS GOES TO GABRIEL AND STANDBYME!!