John finally meets Mary Morstan. She's his perfect match, but when he takes her home and introduces her to Sherlock, her secret is uncovered: her real name is Mary Holmes, and she's Mycroft's daughter. I leave the reason of her lies up to the author.
(That would make Mary a lot younger than John, but I don't care as long as she's +18. Also, I don't know how old is Mycroft supposed to be, but a teenage daddy!Mycroft would be awesome too.)
Bonus points for Sherlock being jealous of their relationship, for Mary being awesome and for a Holmes+John family reunion.
John/Mary (John/Sherlock): inspired by the daddy!Mycroft prompt
(That would make Mary a lot younger than John, but I don't care as long as she's +18. Also, I don't know how old is Mycroft supposed to be, but a teenage daddy!Mycroft would be awesome too.)
Bonus points for Sherlock being jealous of their relationship, for Mary being awesome and for a Holmes+John family reunion.