Archive of Our Own

Their relationship starts when everyone forgets Molly's fortieth birthday, and Mycroft goes out of his way to make her feel special that day. It gets complicated, however, when a few weeks later Molly realizes she's pregnant with Tom's child. Tom wants nothing to do with the baby or the pregnancy, but Mycroft wants Molly and her baby in his life however he can get them, leading Molly to believe, rightly so, that moving on to Mycroft Holmes was the best choice she could ever have made.

Set in an AU that starts between "The Sign of Three" and "His Last Vow," where Molly's fortieth birthday falls in between those two episodes, just a week or two after her engagement to Tom ends. It goes AU before "His Last Vow," but that episode and "The Abominable Bride" play out mostly the same, with Sherlock in the doss house and Molly slapping him, and Christmas playing out the same way. In this AU, Sherlock knows Mycroft and Molly have started dating by December and that Molly is pregnant by then. Series 04 doesn't happen, and Sherlock goes off to find the root of the "virus" that is Moriarty and arrives back just in time for Molly to give birth to her son, so for her pregnancy it's mostly Mycroft, John, Mary and Mrs. Hudson by her side. Endgame ships are primarily Mycroft/Molly but with background John/Mary and a demisexual!Sherlock who is in a long-distance relationship with Irene (for most of the series, at least).