A Twist of Fate (слэш)

In a cocaine bender Sherlock forgets to take his heat suppressants and spends his heat with a soldier readying for deployment. While he remembers the man's kindness he does not remember his name. In a move even Sherlock isn't sure he can deduce, he decides to keep the child.
What will he do 10 years later when he meets Dr. John Watson at Barts?