Chapter 1 - Gemma and Liam

Harry has never expressed his feelings out loud, so he chooses to write them on paper. One day, his love letters are mailed out under suspicious circumstances to all their recipients.

Enter Louis Tomlinson, one of the recipients of said letters, who agrees to a fake relationship so he can make his ex jealous, and Harry can fool his current crush into thinking that the letters were a joke. It's a win-win, really.

(Saw this prompt on Tumblr, and this is based on the book/ film series To All The Boys I Loved, so credit to them)