A/N: Hey everyone! So sorry it's taken me so long to get this next chapter up! But now I should have time to write more, so hopefully it shouldn't be so long between chapters.

Disclaimer: I own only Sheila. The rest of the characters belong to BBC.

Chapter Three:

Impossible

Sheila shook her head. "That's not... No. You... can't. How can you be me?" She stood up abruptly, shoving her chair back. "That's impossible!" She hissed between clenched teeth. She grabbed her coat off of her chair and rushed out of the restaurant.
John blinked, stunned for a moment. He looked over at Sherlock, but saw no answer in his eyes, only a slightly dazed confusion. John slid back his chair. "Sheila, wait!" He called and followed after her.
Sherlock stood more slowly. He slipped on his coat and pulled his wallet out of the pocket, dropping the appropriate amount of cash on the table. He grabbed John's coat and draped it over his arm. He reached for his phone, which Sheila had left on the table, and paused. Hers lay next to his. He collected both of them and slipped them into his pocket and followed after the others.

John ran after Sheila, calling out after her. She didn't stop. She turned a corner, and by the time he got there, she was nowhere to be found.
John stopped, panting, looking around the dark street. He leaned over and rested his palms on his knees, irritated that Sheila apparently shared Sherlock's long legs and and running ability. He turned and headed back towards Angelo's. The cold air nipped at him and he rubbed his hands up his arms in an attempt to warm himself.
He found Sherlock standing on the sidewalk outside of the restaurant with his coat hanging over his arm. He extended it and John accepted it, slipping it on.
"She's gone then?" Sherlock asked quietly.
John nodded. "Yeah. I lost her. I'm sorry." He looked hard at Sherlock, trying to figure out what was going on inside his head. "You alright?"
"What, me? Fine. Yeah, fine. Fine. I'm… fine." Sherlock spoke quickly, sounding the way he did when his mind was whirling, trying to come up with a solution. He started pacing up and down the sidewalk right in front of the restaurant, shoving his hands in his pockets. He stopped pacing and looked down, pulling a cell phone out of his pocket. He held it up so John could see. "She left her phone in there. Same model as mine."
John started at it in amazement. "Sherlock… who is she?"
Sherlock stared back at John, but his eyes didn't seem to pierce through him like they usually did. His gaze held a slight dazed look. "What do you think? She has my memories. She looks like me. She's an amatuer detective; she's intelligent - unusually so…. it points to something unnatural. She has my memories, John. The rest could be a coincidence, as unlikely as it might be, but… my memories." He fell silent for a minute, then scowled. "Oh, quit gawking at me, John! Are we going to try to find her, or not?"
John nodded, and spread his arms out. "Well, where are we supposed to start? She couldn't have gotten too far…" He grimaced. "Unless she got a taxi."
"She didn't get a taxi." Sherlock stared at the phone. He turned it on and the backlight light up his face in the dark.
"How-"
"I just know," Sherlock growled, not looking up.
John raised his hands in a surrendering gesture. "Alright. So, where do you think she is?"
Sherlock switched the phone off and slipped it into his pocket. "Ready to head back to the flat?"
John blinked and stared at Sherlock for a moment. "Sherlock… what? I thought we were looking…"
"She'll find us," Sherlock said. He stepped out into the street and hailed a taxi. John stood on the sidewalk, staring after him.
Sherlock opened the door and slid inside. He looked back out at John. "Are you coming or not?"
John slid inside next to Sherlock and closed the door. Sherlock stared out the window, and as he didn't seem to be interested in telling the cabbie where they wanted to go, John sighed and said, "221B Baker street, please."
Sherlock said nothing the entire ride. John desperately wanted to ask him the questions whirling around in his mind; what was going on, why he'd suddenly decided to return to the flat, and most important - was he alright?
The taxi pulled up in front of 221B. Sherlock opened the door and got out without a word. John stifled a sigh and paid the cabbie, then got out and followed after Sherlock, who had already entered the flat, closing the door behind him.
John opened the door and walked inside. Mrs. Hudson stood in the hall, looking up the stairs, a confused expression on her face.
John didn't bother to stifle his sigh this time. "Evening, Mrs. Hudson."
Their landlady turned to him and smiled. "Good evening, John. Is everything alright with…"
John shook his head. "I have absolutely no idea." He started up the stairs and walked into the flat.
Sherlock perched on his chair, his elbows propped up on his knees and his fingers steepled. Sheila's phone sat next to him on the armrest of the chair.
"Sherlock?" John ventured.
Sherlock didn't respond.
John bit his lip, unsure whether to press his friend, or to leave him alone. Normally when Sherlock got into a silent mood like this, it meant he needed to think. But this time… it was different. John could tell.
This time… he couldn't usually see any emotion in Sherlock's eyes. But now… he could. He saw confusion. And… fear?
John walked over to his chair and sat down across from Sherlock. He glanced at his friend, who didn't show any sign that he had noticed John come into the flat at all. John shook his head slightly. Well, he would be here for Sherlock, even if he didn't know he was here.
Half an hour ticked past without Sherlock moving. John wasn't sure he even blinked.
An hour. Two. Three. John was just about to give up and go to bed, when he heard the creak of a window opening in Sherlock's bedroom.
John looked up, getting out of the chair. He glanced back at Sherlock, who again didn't give any indication he had heard anything. John walked to the stairs and called softly, "Mrs. Hudson?"
No response. She'd probably gone to bed hours ago.
Another slight rustle of noise from Sherlock's room. There was definitely someone inside. John cursed under his breath, and turned to face Sherlock. He waved his hands, trying to get his attention, but to no avail. He scowled, not wanting to speak aloud and let the intruder know he was on to him.
He spotted Sherlock's gun lying on the mantlepiece. He walked over and snatched it. He looked inside, and scowled. Empty. But at least he could look like he was armed.
John walked back over to the door and placed his hand on the door knob…
And the door opened inward.
To reveal Sheila staring back at him, face stony.
John jumped back. "Sheila! What… what are you…"
Sheila crossed her arms. "Good question. I've got a better one. What are you doing here?"
Sherlock's voice came from right behind John. "We live here."
John jumped and spun around, his heart racing. "Sherlock!"
Sherlock raised an eyebrow, apparently mistaking John's cry of surprise for one of reprimand. "What? We do." He turned to Sheila, staring her in the eye. "Why did you run?"
"I came back for my cell phone," Sheila said, ignoring the question, but looking him straight in the eye.
Sherlock held it up and handed it to her. She took it and examined it briefly, as if to make sure nothing had been harmed, then slipped it into her pocket. "Thank you," she said, her voice tinged with sarcasm.
"I knew you'd come looking for it," Sherlock said. "Women have a ridiculous aversion to other people having their phones."
"I do hope you realize it's incredibly rude to look through other people's phones," Sheila said, quirking an eyebrow.
"It was password protected."
"You could have figured it out." Sheila paused when Sherlock didn't answer. A grin spread across her face. "You didn't."
"Why did you run?" Sherlock repeated.
Sheila finally broke eye contact, her gaze wandering around the flat. She finally looked back at him. "I live here. I live at 221B Baker Street."
John frowned. "But you… you can't."
Sheila didn't look at him. "I can see that. I looked through your room, Mr. Holmes - what should be my room. There was no indication that it was mine. It most definitely is yours."
"Then…" John was having difficulty keeping up again.
"Then how do I live here? I don't know. All I know is that I do," Sheila said quietly. "I don't know why I ran. But I know I can't. I have to figure this out. So that's what I'm going to do."

To Be Continued...