A Twist of Fate - Larry Stylinson
Louis and Harry grew up together, and were best friends even in their earliest memories. They are 12 years old when Louis has to move to Australia, and they never expect anything to be the same again.
They make a pact, a promise to one another, put it in a bottle and throw it out to sea. They promise to get back in touch if any of them ever find the bottle again. A silly, childish pact that isn't so silly when you're only twelve years old.
Seven years later, fate turns in their favour. Louis stumbles upon an old, green bottle and Harry just happens to be in Australia as an exchange student. They spend time together catching up, but no amount of time can make up for the seven years they spent apart.
It's almost cruel when you realise the one thing most important to you has been in front of you all the while, yet you never realise.