"No," he said once more.

"John..." she replied, "you're making this much more difficult than it needs to be."

"Don't call me John," he said fiercely. "It's Dr. Watson." Gwen ignored him.

"Come on, I won't ever be a bother."

"We don't know you!"

"As I hear it, you two didn't know each other when you became flat mates."

John shifted uncomfortably at this unfortunately true statement. Currently, John was standing inside the door of his flat while the persistent girl Gwen was standing just outside it, her foot in the door. For some ridiculous reason, this girl thought it was a sensible request that Sherlock and John let her live with them. Sherlock was of course being no help, as he had immediately plopped himself down on the couch upon returning. Therefore, John was left to deal with the nutter.

"The answer is no," John repeated firmly.

"Sally thinks I'm your niece," pointed out Gwen. "What will she think if she finds out that I'm not actually staying with you?"

"First of all, it's Sergeant Donovan, not Sally. Second of all you aren't my niece, so it might very well clear up some confusion that you've caused."

"Yes, but then you and Sherlock would get in trouble, wouldn't you? Is it really worth it?" John clenched his teeth together, feeling trapped and searching for any way out of the situation.

"Come on, Uncle John," said Gwen teasingly, "Just let me in. Then we can talk through things."

Though her name for him rather put him off, John controlled his annoyance and finally opened the door a crack, just enough for Gwen to slide through. As soon as she did, still smiling as friendly as ever, John shut the door.

"Don't look so innocent," he muttered.

"Can we talk now?" she asked. John gave her a curt nod, giving her a look that meant that there was clearly no way to change his mind, but he would still stand there and watch her try. "Here's the deal I'm willing to offer. If you don't let me stay with me, I'll go away and never come back. You'll never hear from me again, I swear."

This girl simply continued to shock John more and more. Did she even understand the concept of bargaining? She'd just offered him the best deal she could have possibly made!

"Fine! Right... good. Do that then," agreed John calmly. John began to move away, done with the whole affair, when he realized that Gwen hadn't moved, just smiling at him knowingly.

"What?" he asked cautiously.

"You can sleep on the couch." John spun towards his flat mate, who had finally decided to join in the conversation. Gwen smiled brightly.

"Merci monsieur," Gwen said gratefully, yet with a teasing glint in her eyes.

"Sherlock, no. No, absolutely not. You are not letting her stay here."

"I'm bored."

"You can't be serious!" cried John. "We know nothing about her! We can't just let her stay with us."

"Dr. Watson..." John turned to Gwen, surprised that she was now addressing him politely. Looking at her, he saw that her self-assured smile was gone. Now she seemed more serious, more sincere.

"I know this doesn't look good," she said, "and I know that I'm intruding on your lives. I can understand why you don't trust me, or like me at all, but please give me a chance. I'm sorry for the actions I've had to take. There wasn't much else I could do. Let's start again?"

Gwen walked over to John and extended her hand.

"Hi, I'm Gwen. It's nice to meet you."

Though John still felt uncomfortable with the whole thing, he felt even more uncomfortable just watching her stand there with her hand out. So he did the sensible thing and took her hand in his own. Her handshake was gentle, not strong as if she were trying to prove a point.

"John Watson."

"Don't you mean Dr. John Watson?" she asked him with a joking, but kind, smile. John smiled reluctantly and released her hand.

"Well..." he said finally, "I suppose I've been outvoted. You should probably go collect whatever things you need to live on."

Nodding, Gwen turned and made her way to the door. She turned one last time to face the room and its occupants.

"Thank you," she said sincerely. "I'll be back soon. Bye Sherlock. Bye Dr. Watson."

As soon as she was out the door and down the stairs, John turned on his flat mate. Sherlock met his eyes calmly.

"You had better know something about her that I don't," threatened John. "That's the only reason I'm agreeing to this. You do know something about her that proves she's not a threat to us, don't you?"

"Oh absolutely." Silence.

"And that would be...?"

"She's in love with us." Silence again.

"Pardon?"

"She's in love with us-"

"Yes, I heard you the first time, I just don't understand why you're saying that."

"Well isn't it obvious John?" exclaimed Sherlock as he leapt up from the couch.

"Well, her interest in us is obvious, but I wouldn't say that she's in love with either of us, and I've certainly seen nothing to indicate that she isn't a threat. I mean... she could be working for... you know who," said John cautiously. Sherlock merely scoffed.

"Of course she isn't. She's in love with us, like I said."

"Feel free to explain yourself at any time Sherlock," said John dully. Sherlock pursed his lips and rolled his eyes a bit.

"She's obviously young, not yet twenty, older than seventeen. The school year just ended so- she's probably just graduated from sixth form. So what does she do with her summer after her last year of secondary school? She doesn't spend time with friends or prepare for uni- no, she's here, following us. She knows who we are, obviously seen my website and read your blog," Sherlock explained, "Then, when Sally asked who she was, she claims to be your relative. So she has picked a role that is very close to you. She didn't claim to be a friend, assistant, or student- no, she decided to be your niece. That implies a level of intimacy, so most likely one that she wants. She has studied us enough to know exactly how best to get what she wants-"

"How do you figure?" interjected John. Sherlock looked at him expectantly.

"Oh come on John! The first thing she does when she meets us is to make herself a puzzle, not revealing her identity or motivations. Right up our alley. Then when trying to get us to accept her into our flat, she threatens to disappear forever if we turn her away."

"And why didn't we do that again?"

"Because then I'll never solve the puzzle!" exclaimed Sherlock. "And she knew that. She knew that I wouldn't let her go without having time to unravel the mysteries behind her." John sighed at his friend.

"Seriously? Sherlock... We should have just kicked her out. That all sounds like guesswork to me. You don't have any solid evidence."

"Well that's just it!" said Sherlock, obviously thinking that his friend was taking much too long to understand something that should be clear. "She has intentionally not given me enough information to understand her. I've managed to piece together only that small bit, not nearly what I would normally be able to tell about a person. So I need her to stay. So that I can figure her out. Then I'll be bored again, and you can make her leave, I don't care."

"I still don't see how you came to the conclusion that she's in love with us," pressed John, "Infatuated perhaps, but-" Sherlock looked at him sharply, seeming confused.

"Well isn't that the same thing?" John did a double-take at the younger man.

"N-... No, of course it isn't the same thing!"

"Oh..." John shook his head at the 'high-functioning sociopath'. Did he truly not understand that there was a difference between infatuation and love?

"Well so is Moriarty, and you can't say that he isn't a threat," said John forcefully. Sherlock sprawled out on the couch and turned his face towards the ceiling, pressing his fingers together.

"Her interest isn't the same... Moriarty's infatuation with me is sick- it's the kind of infatuation that makes him want to destroy us, and he'll have fun doing it. Gwen... her infatuation is more out of fascination and adoration. I promise you that John."

"You better be bloody positive Sherlock..." John muttered dangerously.