Title: Winter's Child
Author: ImpishTubist, Canon_Is_Relative
Fandom: Sherlock
Characters: John/Sherlock, Lestrade, OMC
Warnings: R, character death, injury, illness, mention of child abuse, mention of drug abuse, mention of slash
Length: Novel
Status: Completed
Five years after they meet, Sherlock and John adopt a baby boy.
At AO3
Fuck the description, it does not reflect the great story underneath it.
This story is heart-crushing. I don't know if I'll ever be able to read a Sherlock fanfiction without comparing it to this masterpiece. There are happy moments in which you rejoice with the characters, and there are sad moments that sting so much you think your lung was pierced in the process. Even now, I am fighting with tears. Don't want them to be shed. To me, this is a must-read, one of the works a fan should know.
This is R-rated because of the intensity, the emotional impact it causes.
While I - to this date - am unaware of Canon_Is_Relative, ImpishTubist is one of the finest writers out there I know. Works by that author I can recommend:
They're Gonna Be All Right ( Lestrade/Sherlock)
The Coming of The Night (Lestrade/Sherlock)
A Memory that Never Forgets
The First and Only Convention of the Scotland Yard Matchmaker Committee
The Fall of Gods
An Age of Silver