A/N: Based on a tumblr post;
"After the fall, Sherlock ends up with brain damage. He struggles to speak and function properly, but John still loves him and looks after him. and Sherlock is still clever, still spends his time experimenting and playing the violin, but there's a childlike aspect to him that John knows is uncharacteristic and wishes wasn't there, and sometimes he'll just sit and sob, but he's grateful still because Sherlock is here with him so he knows he has to appreciate what he could've lost but he feels like he's lost it anyway."
"Here, take your pills." John offers a palm full of capsules to Sherlock. His outstretched hand ignored as Sherlock pokes at a fibre sample under the microscope.
"Sherlock. Come on." John says. "After breakfast, we agreed."
He frowns but turned away long enough for John to tip them all into his mouth.
He pushes a mug forward. "Swallow."
Sherlock spits them all out, into the mug.
The heavy ceramic hits the table hard and a stack of papers flutter off.
"Why the hell did you do that?" John asks, louder than before.
Sherlock knits his eyebrows, "That's what you said. I did what you asked."
Silence.
"Christ." John lets go of the handle and places a hand over his eyes. "I'm sorry, Sherlock. I didn't mean to- I just, sorry. Sorry."
He walks back to the medicine cabinet and reads off the paper taped to the mirror. John returns with a glass of water and the same combination of medication in his hands. He picks up a page from the ground and a pen.
Please swallow the pills.
Sherlock's frown returns, eyes downcast. "Is that what you said originally?"
"It's my fault, I forgot what the doc-"
He stops talking when he sees Sherlock's face.
John sighs. "It's alright. We'll get there."
"Um," Molly laughs like she normally does. "John tells me you're running out of experiments, we've got a fresh one just this morning. Car accident, perhaps you'd like to stop by? We could catch up, have some coffee?"
"What about now?" Sherlock steps forward until Molly has to crane her head in order to look at him. "Are you busy now?"
"No, I- I guess not. What, what are you- uh." Molly flushes. "Sherlock."
He bends down to kiss her, arms already wrapped around her waist.
Molly kisses back at first but soon pushes him away. "Sherlock, you can't- I fancy you, I know you know, but wha- I mean," She laughs again, the pitch is higher. "You and John… it's obvious, even from the outside."
"John said no."
Molly's eyes widen, she opens her mouth to speak but-
"He said, 'not like this'."
John is typing up a new chart for the medicine cabinet mirror when he hears glass shatter. He walks into the sitting to find Sherlock curled up on the floor, knees drawn and hands pulling at his hair. Shards of teacup and saucer litter the ground right by the coffee table. His shoulders are shaking.
John walks over, places a hand on his back, and says nothing.
"The table was right there, I saw it." Sherlock whispers.
"The floors in this flat have seen a lot worse than spilled tea." John smiles like he did in that family photo Harry wasn't invited to and mops up the mess.
Later, they sit on the sofa.
"How can I observe when I can't even trust what I see?"
John cards his fingers through Sherlock's hair.
"I wish I had died."
"Amnesia seems like the lesser poison."
"But then you wouldn't know who I was. We'd have to start all over again."
"As opposed to now?"
"I haven't lost you."
"Completely. You haven't lost me completely." Sherlock says. "I'm half the person I used to be."
John stares.
Sherlock replies, "I know. Half is being generous."
Greg finishes his pint and thinks he's drunk enough. "We can't avoid it all night, how is he?"
John is on his fourth, "Sherlock wanted to fuck."
"Another." Greg waves to the waitress.
"To be honest, regardless of the birds you pulled, we all thought you two were shagging a bloody long while ago."
"I couldn't do it. I can't bloody do it." His words slurred.
"The way you use to look at him? Could've fooled me." Greg quirks the corner of his lips. "But hey…"
"No, no. It's not that. If he'd asked before, when he was sti-" John shakes his head then looks up at Greg. "I loved him."
The waitress still has not arrived. "Not much of a secret, that." Greg chuckles, then tags on a question. "Loved?"
John blinks, he did not misspeak.
Mycroft sits in John's chair with his legs crossed.
John can't hear what Mycroft is saying but knows that he is the only one speaking.
Lestrade texts Sherlock about a crime scene, it's a relief for everyone.
John goes along like before, examines the body like before, but things are not like before.
Anderson and Donovan wear no explicit expression and says nothing to Sherlock when he yells at them to leave the room.
When Sherlock goes to step over the corpse, he ends up stepping on the dead man's outstretched arm. John takes Sherlock's arm and leads him around, quietly telling him that they've already taken photographs.
Sherlock watches John dust away the shoe print pressed into the elbow of the victim's dress shirt.
When Sherlock goes to grab his magnifying glass, the one right beside his knee, his fingers close around nothing.
John sees a latex gloved hand reaching for an object two floor boards away, he walks over, picks it up and presses it into Sherlock's hand.
When Lestrade comes back in, Sherlock begins to talk about the wallpaper. He doesn't speak as fast as before and occasionally uses the wrong words but John understands.
"The hands." Sherlock says, and points at the victim's hands. "The hands."
"Is there something wrong with them?" Lestrade asks and looks at John.
"They look fine to me. Did I miss something, Sherlock?" John crouches down again to study cuticles, joints and weathered skin.
Sherlock shakes his head, jaws clenched. "The hands!" He says again.
They try for another four minutes, but Sherlock only repeats the same thing (louder and louder) and John does not know what else to do.
"Hey, relax. It's Okay." John says to him.
Sherlock stares with watery eyes, he opens his mouth but no words come out, only heaving breaths. When he tries to leave, he walks into the door frame and falls backwards.
John rushes to him, "Sherlock, are you alright?"
"Don't." Sherlock pushes John away. He reaches forward to feel for the frame this time and walks out.
Later, they notice the watch on the victim's wrist had stopped running right around the time of death.
Sometimes, Sherlock will cry and break things, anything he can get his hands on.
John always hides the violin during tantrums because Sherlock will always play it afterwards. The instrument makes a decent messenger, and John is pretty sure it's an apology.
Sherlock plays loud enough for John to have a turn.
"I remember what I used to be like, before." Sherlock says one morning.
"Hmm." John hums and smiles, reading the paper. "Don't worry, Sherlock, you were always a dick."
"Yes." He positions the violin under his chin. "But I wasn't always a burden."