AU in which Sherlock is an asexual/ demisexual Omega who doesn’t have heats in the same sense other Omegas do and John is a rare Beta. The two of them get introduced by Mike who is aware of Sherlock’s avoidance of Alphas (Who tend to think they can cure him). At first Sherlock is a little wary of John because he acts more like an Alpha but they become close friends.

John ends up falling head over heels for Sherlock and at first he worries because Omega/Beta relationships hardly ever work out because Betas can’t knot, have lower libidos and sometimes infertility. Things John has been told before make him not mate material.

Sherlock meanwhile is scared of telling John, worried that he might think Sherlock weird and leave, something Sherlock can’t bear the thought of, having become used to John’s jumpers and tea. Sherlock can’t help but want John to stay and be with him, even if he doesn’t really have an interest in sex.

Some angst but they work through things together.