"Sherlock?" Joan called out as she entered the Brownstone. When there was no response she went looking for him. She started upstairs and continued down stairs. She ended up in the living room with no sign of him. She let out a sigh and got her phone out of her purse. When she did she saw a strange light from the corner of her eye. She turned to see it and was blinded. When she woke up she was on the floor of an unfamiliar living room.
Earlier that day John had been out getting the groceries when Sherlock had left. When John got back he put all the food away in the kitchen. He saw a strange light out of the corner of his eyes and turned to see it and was blinded. When he opened his eyes he was standing in a very unfamiliar living room.
"What the hell." He mumbled to himself. He looked around and tried to figure out where he was and how he'd gotten there.
While John was doing that, Joan was copying his train of thought exactly when Sherlock walked in. Joan tried to think of what she was going to say to this stranger about her being in his living room but no words came out.
"Who are you?" Sherlock asked. "Where's John?"
"Who's John?" She asked thoroughly confused.
"I asked first." Sherlock said as he looked around. He took out his phone and texted Lestrade.
"I'm Joan Watson, and I don't know anyone named John." She said. "I don't even know how I got here. One moment I was in the Brownstone then I was here."
"You expect me to believe that you have the same last name as John but you don't know him?" Sherlock asked with narrow eyes.
"People can have the same last name without related or without knowing each other." Joan said.
"You're saying that it's a coincidence." Sherlock stated.
"Yes." Joan said.
"There's no such thing." Sherlock told her harshly. "Now where's john."
"I told you I don't know anyone named John." She said. "And I don't appreciate your attitude. It's been a long week and I've quite frankly had enough. Who are you anyway?"
"Sherlock Holmes." Sherlock replied cautiously.
Meanwhile Sherlock had just gotten back to the Brownstone. He knew that Joan was going to be mad at him for not telling her he was going out that morning. He noticed the signs that she had arrived and entered his home.
"Joan." He called out. "I know I didn't tell you where I was going. It was nothing really. Just had to pop out for a bit, went on a jog."
He entered the living room where he found John. They stared at each other for a while. Neither knew what to say so they just stood there. Sherlock kept opening his mouth to say something but no words came out.
"Look, I'm not a burglar or anything." John said. "I don't know how I got here. One minute I was in my Flat the next thing I know I'm here."
"Oh, well have you seen an Asian woman around?" Sherlock asked him. "Her name's Joan Watson."
"No I haven't, sorry." John said, he seemed surprised that the woman this man was looking for had the same last name as him. "It's odd though, my name's John Watson."
"Really?" Sherlock asked intrigued. "Very strange, maybe you and my Watson have accidentally changed places."
"I don't follow." John said. "Who are you?"
"It's alright most don't." Sherlock said. "I'm Sherlock Homes."