Louis and Harry may seem just like best mates, and maybe that is all they are for now. Harry is only sixteen after all, and Louis' is too busy focusing on having fun than falling in love.
In the future, though, they are so much more. They are so madly in love it's impossible to seperate them, but after the accident they both know that something needs to change.
Time travel is a common thing, something everybody in the future does. Louis and Harry never wanted to change anything, but after the accident they both know they can't keep hiding their love from the world, so Simon gives them one chance to go back in time and stop younger-them from signing the contract with Modest!.
If you had the chance to change your fate, would you?