It had been talking to John for months now. Ever since it was just a fuzz above his lip, whispering, softly at first, before it grew bolder. John had long since accepted his descent into insanity.
At least the mustache kept him company. And it was a much less obtrusive flatmate than Sherlock ever was, truth be told.
The mustache began on a whim, as a testament to John's new beginning. It made him look like an older, wiser, sexier John than the one that had appeared at Sherlock's side in the tabloids. He hardly even got recognized on the street anymore.
John named it Perry.
Perry whispered good morning to him when he woke and goodnight before bed. That was how it started, and for a short while John thought it was all in his head, or that he was dreaming it, but then it started happening in the daytime. When people were around.
"Look at those tits, John."
"Ask her to lunch, John."
"Back to your flat, John."
Perry was a terrible influence on him. John couldn't even be around a woman now without blushing horribly, because if there was a woman near him, Perry would be talking about her. John didn't think it was malevolent. Basically just locker room stuff. It was harmless, really, and he'd actually gotten a few dates because of it.
One night, late, John stood staring in the bathroom mirror, a razor in his hand.
"What are you doing, John?" Perry asked.
"I'm insane," John replied, calmly as he could.
"You're not crazy."
"I am. I am talking to my mustache."
"You're not crazy," Perry repeated. "You're lonely."
John didn't shave. They fell into an easy routine. He would wake up (Perry would say good morning), go to work at the clinic (Perry would help him with his diagnoses), go get coffee (Perry would tell him what to say to the barista, or the pretty girl in line behind him, or the brunette reading a book), and together, the three of them, would go on a date.
John had never had such a successful love life. But it didn't make him less lonely.
He still dreamt of curly hair and icy eyes and greatcoats. Over time, Perry's voice grew deeper, more cultured, and John had to admit that his mustache was beginning to sound a lot like Sherlock. That made it even more impossible to shave.
In the middle of one his longest clinic shifts, John received a text. He didn't recognize the number and neither did Perry, but it could've been a girl they hadn't spoken to in a while. It said, simply, Dinner?
John accepted. After his shift, he went home and combed Perry flat against his lip. The restaurant the woman had suggested was nice, classy, so John would have to wear a suit. He hadn't worn one since court dates with Sherlock. John was alarmed to find it was tight around the waist.
Perry soothed him. John looked very smart in his suit, very smart indeed, and the woman, whoever she was, would be happy to have his company. Even if only for the night.
At the restaurant, John sat in his suit and stared at the candle on the table. Remembering another time candlight made a dinner more romantic.
John felt him before he saw him. It was a warm blush on his neck; goosebumps spreading up his arms. His fingertips going numb. He brought his head up. Perry screamed.
Black curls and shirt; gray greatcoat and blue eyes. Cheekbones that would make a model stop and stare. The things that added up to equal Sherlock Holmes.
Sherlock with his coat collar turned up in the way that drove John crazy. With his scarf tied just so. Looking at John. At Perry.
John felt himself go empty.
His phantom Sherlock moved closer. John shrunk against the booth.
He was insane.
This was not real.
Just another step taken toward asylum, somewhere they'd put him in straightjacket and a room with padded walls. That would be comfortable. That would be nice. John would like to go there.
He stood. Calmly stepped toward the ghost that was his best friend and the only man he had fallen in love with and God, his heart, it ached—
John balled a fist, stabbed his elbow back, and punched him.
It hurt.
He was solid.
Solid. People were staring. People could see him. Them.
Perry was still screaming.
"John—" Sherlock said, and suddenly John was much too dizzy to stand, and much too overwhelmed to be conscious.
That night, back in 221B, John and Sherlock sat at the kitchen table.
"The mustache will have to go," Sherlock said.
Perry hadn't made a sound since John had regained consciousness. He was alone in his head now, and he was okay with that. He might miss Perry a bit, just at first, but having Sherlock back... John would've given an embarrassing amount for Sherlock. Anything. Everything.
Of course, Sherlock knew that.
"That's fine," John said.
"John–" Sherlock said, squinting at him, "why would you ever grow such a thing?"
"Women seemed to like it."
Sherlock hmmed. "You were more handsome without it."
John's heart expanded so large he was surprised his ribs could contain it.
"You think so?" he said.
"Yes," Sherlock said. He licked his lips and suddenly John couldn't stop staring. "I missed you."
"God, Sherlock. I missed you too."
John hadn't realized he was leaning in until he was a handful of inches from Sherlock.
He froze.
Sherlock breathed in. "John," he whispered, voice low.
"Yes?"
"I would like to kiss you."
"I'd like that too."
"But first you must shave."
John never grew another damn mustache.