John and Sherlock get married...and literally nothing changes. Your challenge: Totally platonic. No slash. No romance. No friends to lovers.
Maybe they've gotten tired of calling Mycroft every time they need something legal set up (like medical power of attorney). Maybe they've looked at all the options in society and say a marriage is the closest thing to fulfilling their needs (legal, social, whatever). Maybe they say neither one of them are probably going to marry anyone else, so why not make it official that they are a (platonic) pair. (I don't care what you do with Mary in this scenario.)
But overall, their lives don't change at all. Still separate bedrooms. No kissing the groom at the registrar's office. No changing of last name. You get the idea.
John and Sherlock: Platonic Marriage
Maybe they've gotten tired of calling Mycroft every time they need something legal set up (like medical power of attorney). Maybe they've looked at all the options in society and say a marriage is the closest thing to fulfilling their needs (legal, social, whatever). Maybe they say neither one of them are probably going to marry anyone else, so why not make it official that they are a (platonic) pair. (I don't care what you do with Mary in this scenario.)
But overall, their lives don't change at all. Still separate bedrooms. No kissing the groom at the registrar's office. No changing of last name. You get the idea.
Bonus +1: Someone unexpected (Mycroft? Donovan?) thinks it's a brilliant idea.
Bonus +5: "Three Continents" Watson finds a way to use his new status to pick up women.
Bonus +10,000 and I will name my puppy after you: Sherlock finds a way to use this to pick up women!
Crack accepted and enjoyed but not required!