When the penny drops (слэш)

Every person on Earth has a soul mate, but only about one in forty meets theirs. And some find theirs more than once before it sticks.
The first time John meets Sherlock, he has just turned six and Sherlock's age is still legally counted in months.
The second time they meet, John is twelve and lets a bossy child pretend they're pirates looking for treasure.
After the third time he will remember Sherlock's name.
By the fourth time John is convinced he's lost him for good but the fifth time is the one they make it count.
Soul mate AU in which the boys have always been pulled to one another, but it takes them 32 years to realise what that actually means.