queer-until-proven-straight:
Charlie Welsborough is a trans lesbian who was planning to come out to her parents when she got back from traveling.
“Travel broadens the mind” is one of the first things we hear her say, on a pre-recorded video. Charlie would like her parents’ minds to be broadened, so that they would accept her rather than meet her with transphobia and homophobia. Charlie recorded this video of herself pre-transition, because she’d like to come out to her parents in person.
Sherlock immediately deduces that Charlie is trans. When he meets the Welsboroughs, he says, “I really am most terribly sorry to hear about your daughter.”
When Sherlock is corrected, he realizes that Charlie isn’t out to her parents yet. Not wanting to posthumously out Charlie, Sherlock doesn’t comment further – especially when he notices the Thatcher shrine and realizes all the misgendering and other forms of transphobia (and homophobia as well) that Charlie would have been exposed to from her parents. This, however, does explain why Sherlock is so petty to the parents. Sherlock hates homophobes and transphobes.
Sherlock describes Charlie’s plan, but doesn’t tell the parents the full story, instead describing Charlie the way the parents knew her. (Sherlock as an unreliable narrator would also fit with the rest of episode, especially if the alibi theory or some form of it turns out to be the explanation for TST.) Sherlock doesn’t explain that Charlie’s “surprise!” (complete with the rainbow across her face – why Charlie is not only trans but also a lesbian) was a plan to come out to her parents.
@marcelock @quietlyprim @kajepan @ anyone else who supports trans headcanons / meta