They get married for a case.
Well of course they do, of course they get married for a case, however farfetched that is, and the only thing surprising about this is how long it took Sherlock to find a case for which to get them married. A little over three years is how long, three years since they met, but he’s only been keeping an eye open for one for the last year. It’s still surprising.
Source: The Important Bit, by Solshine – Sherlock (TV) [Archive of Our Own]
Rated G, asexual!Sherlock/straight!Watson marriage fic. 30 years of domestic bliss neither one of them expected (John less than Sherlock).