Sherlock Holmes and Dr. John Watson returned to their residence of 221b Baker Street in a very cheerful mood, they had just wrapped up a case involving a clown, an overgrown parsnip and poison. Sherlock was well… Sherlock about the whole thing and being awfully smug how right he had been about the whole thing. John was certain that he was living in what monopoly and cluedo would be like if they had been merged together. Stepping into the flat John was surprised to see a teenager girl with long dark hair pulled in pony tail dress in a school uniform consisting of a white shirt, pilot blue jumper and a blue tartan skirt, black tights and school shoes walking around the flat aimlessly. "Excuse me but who are you?" John asked.

The girl stopped in her tracks and glanced briefly at Sherlock before her eyes returned to John. "Shouldn't you be asking how I got in here?"

"W-well yes, that would be a good place to start." John admitted before pulling himself together. For some reason this teenage girl was making him feel very insignificant and small just by her presence, in his own home! There was something about this girl that was very familiar but John, for the life of him couldn't figure out why. "So how did you get in here?"

"If I gave you the answers where would the fun be in that? You are after all the detectives but I'll give you a clue; it wasn't your landlady Mrs. Hudson. She's been home for an hour and yet to realize that I'm here, quite amazing actually seeing as i've managed to have two cups of tea in that time..." The teenager quipped as she chuckled quietly.

"Okay. You manage to break into our home, help yourself to tea and you want us to figure out why? I have to admit that's a new one…"

The teenager just shrugged her shoulders as she sat herself down in the armchair that faced away from the window and usually favoured by Sherlock. "What can I say? I like to break people out of their norms and have them experience things from a different perspective. And as true as what I just said is, really this was the only way of surprising you that I could up with in the cab on my way here. I was pressed for time you have to understand…"

"I really have no idea what's going on here and what you want." John admitted.

"John. Shut up." Sherlock said for the first time since they had come across the teenage girl in their flat and with a small frown on his face, Sherlock made his way to the other armchair in the room and sat down, where the teenage girl turned her attention to him now. She was the last person he expected to see here of all places and clearly she was up to something; it was just figuring out what she was up to, that was the problem. She knew all of his tricks; he knew it and so did she. So Sherlock chose to do nothing except sit there.

The two of them sat there staring at each other from opposite ends of the room, their eyes never leaving each other's once except for the occasion when they needed to blink and even then they blinked less then the average person. Blue eyes met blue eyes and neither seemed willing to back down until an hour later when the teenager got a message on her phone and her eyes darted away to read the message before returning her gaze to the subject of her scrutiny. "Sherlock." She finally said.

"Cassandra."

"You two know each other then?" John summed up as glanced out Sherlock and the teenager now known as Cassandra who resumed their staring contest. Since he had met Sherlock, John had come across many things with the rather odd and eccentric man which never seemed to make that much sense but John went along with it. But watching Sherlock having a battle of the wills with a teenage girl that he somehow knew was something he really could not fathom. As how the hell did Sherlock Holmes know a teenage girl? "How do you two know each other?"

"Uncle." Sherlock announced rather uncomfortably as he rose from his seat and made his way over to one of the large windows that occupied 221b Baker Street.

"Niece." Cassandra added with even less enthusiasm as Sherlock as she absentmindedly looked at her nails with a bored look spread across her face.

John was shocked at this news to say the least as the only relative he knew of Sherlock's was his brother Mycroft and neither of them had ever mentioned any other relatives except for 'mummy' in passing and how their arguing upset her. John would have asked if this was a joke if it wasn't for the fact that the consulting detective and teenage girl wore almost similar looks of despair on their faces. So they were in fact Uncle and Niece and they both didn't seem to happy about it. "Sherlock you're an Uncle?"

"Unfortunately. Did I neglect to mention that Mycroft had a daughter? A teenage daughter who has a perpetualant habit of getting kicked out of school because she craves daddy's attention." Sherlock replied in a deadpan tone, still gazing out of the window.

"Mycroft is your father? You're a Holmes…" John asked the teenage girl and now it all made perfect sense to him. The attitude, the know it all look that Cassandra had on her face when they arrived was definitely Mycroft with a mix of Sherlock. Then there was the whole deduction thing that seemed to be an innate Holes trait and then the pale complexion, blue eyes and dark hair that Cassandra had as did Sherlock and Mycroft. No doubt about it; the teenage girl in their flat was definitely a Holmes. She was a mini Mycroft with the eccentricities of Sherlock. John found this to be very odd, bizzare and yet utterly fascinating at the same time.

Cassandra slowly rose from her chair and held out her hand to John. "Yes I am and I assure you it wasn't my choice. It's a pleasure to meet you Dr. Watson, I'm Cassandra Holmes."

"Enough with the pleasantries." Sherlock interrupted as he turned around to face his niece who was just like her father when it came to running circles around people before turning on the charm. "Cassandra what are you doing here? Aren't you supposed to be in some boarding school in Scotland or have you been kicked out again? Does your father know about any of this?"

"Of he course he does this is Mycroft were talking about, he knows everything including what colour socks I'm wearing today." Cassandra replied in the same exasperated tone that John had seen both Mycroft and Sherlock used when they were questioning the intelligence of someone who clearly wasn't as smart as them.

"Yellow–" Sherlock began.

"Actually it's one yellow sock and one green sock. Must be getting rusty in your aging days dearest Sherlock as you've seem to forgot that I favour wearing odd socks and I'll have you know that I've been at boarding school in Winchester and no I haven't been kicked out, yet…" Cassandra replied with a rather smug grin on her face.

"Doesn't explain why you're here, would you care to explain that Cassandra?" Sherlock questioned as he had been having a rather good day until the arrival of the mini she-Mycroft and to be honest he wasn't in the mood to be dealing with his frequently difficult niece.

"The great detective can't figure it out?" Cassandra taunted in a rather amused manner before rolling her eyes in bemusement.

"You don't know yourself, do you?" Sherlock figured as Cassandra was still in her uniform and her school bag on the floor. Both of which were things you would not wear or bring with you to a planned trip to London. So that meant that this trip was unplanned and there was only one person who would bring Cassandra Holmes to London this unexpectedly. And that was his brother and her father; Mycroft Holmes.

"Afraid not."