This is by H28 on onedirectionfanfiction.com it's wonderful and I hope you like it as much as me. Recommended for 17+

Resolution is the story of when a chemical, strictly-physical relationship evolves into something so heart-wrenchingly real that Harry and Halle's worlds are changed forever. If you want to feel, really feel, read it. WARNING: Extremely explicit sexuality. Please only read if you are comfortable with mature content. All Rights Reserved to styleslegend, 2018 ©

My thoughts you can't decode.. Sequel : Escape Route.