They arrived home at the same time.

Mrs Hudson was at the door to greet them.

"Hello Mrs Hudson," John said.

Sherlock nodded to her.

She beamed at them. "Hello boys," she replied, her eyes flickering back and forth between them. But never looking at them.

They climbed up the stairs silently, and stood in the living room.

"I've had an awful day," John admitted.

"Me too," Sherlock sighed.

"Pretty sure mine was worse," John muttered.

"I doubt that," Sherlock replied. "You go first."

John sighed heavily, as though the very act of telling may exhaust him. "Lestrade told me that you aren't real. That I invented you, and that he's my therapist, and Mrs Hudson is a nurse."

Sherlock's eyes widened. "He told me that too."

John frowned. "That you don't exist?"

Sherlock shook his head. "No, that you don't exist."

John considered that for a moment.

"But I do," he whispered.

"And so do I," Sherlock whispered back.

John wrapped his arms around Sherlock for a hug, and was surprised that the other man hugged him back.

He felt so real.

Tears began to sting John's eyes. "I don't exist," he whispered, arms still around Sherlock's neck.

"So I'm told," he murmured back.

"And you don't exist."

"That's correct," Sherlock confirmed.

"Then let's not exist together."

"Yes," Sherlock agreed. "That sounds good."

And so both of them, or neither of them if that was the case, held the other tightly and willed the world to go away.

Or maybe it was never there to begin with.