Do NOT read this Sherlolly ficlet unless you've a) seen Avengers Infinity War or b) don't give a fig about Avengers Infinity War. MAJOR spoilers for the end of the movie. Also much angst. And MCD. You have been warned. Rated K+
It happens suddenly, in the course of a single five minute period. Half the world's population just…gone. Vanished into dust, blown away by the breeze or left in heaps, indoors and out. Every continent, every country, across age, race, sex, any barrier you care to name. Rich and poor (the three youngest British royals are now orphans to be raised by their bewildered and grief-stricken uncle and his new bride), young and old (horrified nurses at Mass General and many other hospitals around the world screaming as babies swirl into dusty nothingness before their eyes), male and female, friends and enemies, all gone.
It happens in front of Sherlock's disbelieving eyes: one minute he's taking a giggling, two-year-old Rosie Watson from her father, the next John is just…gone. A pile of dry leavings on the carpet in 221B's sitting room, looking like nothing more than a mess for Mrs. Hudson to hoover up.
Except Mrs. Hudson is gone as well, and his brother Mycroft and their parents, even Eurus is gone, leaving Sherlock as the last Holmes standing. Rosie is screaming in his arms and he's frozen in shock as he stares at the place where his best friend just was, wondering what he'd taken to cause such an hallucination. He's stayed off the sweeties since Sherrinford, not only for his own sake but for everyone whom he loves and is loved by.
That number is now down to a bare handful. Rosie. Lestrade (but not Sally Donovan, she's shriveled up and died just like the others, Anderson and Dimmock and a full quarter of the Met's uniformed officers). Wiggins is still there, for whatever that's worth.
And Molly.
Molly Hooper has survived the destruction. Molly comes pounding up the stairs to his flat while he's still flailing, still trying to process the impossible, still unable to do anything to calm his goddaughter. She tears into the room, tears streaming from her eyes, sucking in a panicky breath at the sight of what used to be John Watson lying on the carpet, but the naked relief in her eyes as she gasps out, "Sherlock! Rosie!" is almost too much to bear.
He sinks to his knees, into her embrace as she rushes across the room and flings her arms around the pair of them. Rosie stops howling (but not crying) as she puts her little face against her godmother's neck, taking comfort from the single grown-up not incapacitated by the impossibilities of this terrible, terrible day. Sherlock can't fully relinquish her, and Molly doesn't even try to pull the sobbing toddler from his arms, just holds them both close as if terrified to let either of them go.
Since they're equally terrified to let her go, it works out.
The huddle together like that for nearly an hour, Rosie eventually falling into a fitful sleep and the two adults praying (he never thought he'd pray again, hasn't done so since reaching the age of reason) that this isn't just the first wave of - of whatever it is that's happened.
(They don't find out what it is until days later, when the attack on Wakanda is made public, that it was quite literally genocide perpetrated by an alien madman across not only this world, but every inhabited world in the galaxy. By then they're too numb to care about the why and how, only about their own personal losses, the who on a local level difficult enough to conceive without trying to expand their sense of loss to include alien others on worlds they've never heard of.)
"Molly," Sherlock rasps when he regains his ability to speak, hours later. After they've settled Rosie in her travel cot, set up in the sitting room so they can watch her, both knowing how utterly helpless they'll be to stop it if it happens again, if she's taken from them the same way her father was, but needing to see her. To know if it does happen, immediately, but thank God it doesn't. Rosie is safe, they are safe, everyone who was going to be taken is already gone.
(Mrs. Hudson is gone, they know about her because they all three went down to check on her once they could pry themselves apart from each other, and the sight of that pile of dust in her kitchen, settled on the floor and the table and the chair and drifting in her cold cup of half-drunk tea…that sight was one that would haunt Sherlock and Molly forever, thank God Rosie was sleeping and too young to understand even if she'd been awake and…)
"Molly," he says again, fighting to unsee, to delete from his Mind Palace, what he's seen today.
He doesn't realize he's crying until her fingers are on his cheeks, her thumbs wiping away the fat wet drops falling from his eyes. She's long since cried out, her eyes red and swollen, her throat dry and scratchy, her grief and horror (she watched Mike Stamford and three interns disintegrate before her very eyes in the Path Lab, saw dozens more dissolve as she raced out of the hospital and down the street, desperate to see Sherlock and Rosie and John - oh GOD, John! - but she does what she always does.
She helps him. She holds him, she kisses him, she makes him feel fractionally less disoriented, fractionally more anchored. She's his constant and she hasn't been taken from him and she won't be taken from him (he eventually learns along with the rest of humanity).
"Sherlock," she murmurs, holding him close, her eyes on Rosie, sleeping so innocently, her thumb in her mouth, her cheeks red and blonde hair tangled.
They hold each other, and watch their goddaughter, and try their best to just keep breathing and living and surviving the end of the world as they've known it.