So imagine nineteen-year-old Sherlock bringing twenty-two-year old John home for the holidays. Sherlock would lead John into the kitchen where Mummy is busy cooking a special dinner for Sherlock’s arrival (even though she knows Sherlock will hardly eat any of it), and Papa is reading the paper, and they would both look up, ready to say “Welcome home!” but they’d freeze at the sight of John.
The sauce in Mummy’s ladle would be dripping onto the floor, and Papa’s paper would sort of wilt, and John would just be standing there, looking confused, and Sherlock would say as tersely as he can, without meeting anyone’s eyes, “Mummy, Papa, this is my…this is John Watson. He’s come to stay for the holidays.”
And Mummy and Papa would just continue to stare for a few long, painful seconds during which John hisses to Sherlock, “You didn’t even tell them I was coming?!” and Sherlock shrugs, and John just glares at him briefly before smiling sheepishly at the Holmeses and stepping forward some. "Sorry to barge in on you like this, someone was supposed to tell you I was coming" and he throws another glare over his shoulder at Sherlock, “but he evidently forgot.” And Sherlock just scowls and crosses his arms.
Mummy Holmes just stares at John for a long moment, still completely thrown, and then she finally shakes herself a little bit and says, “And you’re…a friend? Of Sherlock’s?”
And John’s lips quirk up into a happier sort of smile, and he says, “Well, boyfriend, actually,” and that’s when Mummy drops the ladle and sauce goes spilling onto the floor, and John is nearly knocked over by the force of her rushing past him and yanking Sherlock into her arms, tears in her eyes, and Sherlock is flailing and trying to push her off–“Mummy, stop it, you’re being ridiculous!”–but she’s got him held tight, and he eventually gives up and just sort of goes limp while she squeezes him and tells him she’s never been happier in her whole life.
John is staring at this spectacle, bewildered, when Papa Holmes comes up to him, hand outstretched and says with a smile, “We’re very pleased to meet you, John.” And John reaches out to take his hand, but before he can he’s suddenly enveloped in Mummy’s embrace, and he’s sure he’s blushing bright red, and he can see Sherlock over her shoulder, looking ruffled and irritated and achingly adorable. John pats Mummy’s back awkwardly and says, “So I guess Sherlock doesn’t bring guests home very often…”