Chapter Eight: Warning

A/N: This is quite an exciting chapter as a few interesting things are revealed, so we hope you enjoy it. Sorry it's taken a while to update, it was a long one to write.

We seem to be lacking in reviews for this fic, so we would really appreciate it if you took the time to let us know what you think.

Disclaimer: As you should know by now, we definitely don't own.

Sherlock drummed his fingers against the armrest on his chair as he impatiently waited for John to return from seeing the doctor. The man seated next to him sneezed loudly, causing Sherlock to lurch away from him, waking Molly who was sleeping on his shoulder as he did so.

"Oh my God, I'm so sorry…did I fall asleep on you?" Molly quickly apologised.

"Yes."

"Oh, I'm so sorry Sherlock," Molly blushed.

"Yes, you just said that," Sherlock acknowledged as he turned his attention to the culprit who had just sneezed on him. "You know it's really not necessary to come to A&E with a cold, its people like you that lead to traffic jams such as these in the emergency rooms of this country," he said furiously.

"Actually I'm not here for a cold, I'm here due to a very painful incident involving a vacuum cleaner!" the man argued defensively.

"What?" Lestrade exclaimed in confusion.

"Oh, apologies," Sherlock replied, "I understand now, but you could still help avoid these delays by using a safer method of foreplay in the future."

"Did you just say what I thought you said?" Lestrade asked, shocked.

Sherlock ignored Lestrade's comment, and jumped from his seat as he saw John finally emerge. "John, at last!" he exclaimed, eager to leave the hospital.

"Yes…" John began; about to explain what the doctor had said before Sherlock interjected.

"Come on now, let's leave. We don't want to waste any more time here," he said as he began striding out of the waiting room.

"Yes right, of course we don't want to waste time," John agreed satirically.

"Are you ok John? What did the doctor say?" Molly asked sympathetically as they walked out of the hospital.

"It's not septicaemia. Just a mild infection, the name of which escapes me now; I was practically nodding off while I was in there. He gave me a bit of a telling off for not looking after it but he didn't seem too concerned. He's given me a prescription for some antibiotics and so I should be right as rain in a few days."

"Oh good, that's good, very good," Molly smiled at him.

"Yes," John agreed with a yawn.

"Oh let's get you home, you really need some rest," Molly mothered.

"Yes, you must be quite tired yourself, what with waiting for me all this time."

"Yes, I am, in fact I actually fell asleep on Sherlock a minute ago!" Molly confessed.

John's surprise in concern to this revelation caused him to knock into a fire extinguisher which was mounted on the wall. "What and he let you?"

"Oh goodness, are you alright John?" Molly said, concerned that he had just injured himself further.

"Yes, yes I'm fine. Just clumsy, that's all," John explained. "So when you say you fell asleep on him, you mean actually on him?"

"Well I didn't intend to. I woke up when he jumped up so I must have had my head on his shoulder, I think."

"Wow. He usually gets edgy when he has to shake someone's hand; he's not really a fan of human contact in any form."

Before Molly could reply, Lestrade charged towards them, "Could you two please hurry up, I'm not being funny John; I know you are injured but I've already spent five hours in A&E and I'd really like to get home before sunrise!"

"Yes of course," John said apologetically and began to walk faster, "thanks so much for driving me here, I really appreciate it."

"Yeah," Lestrade said as he tried to hurry him along.

"Is everything ok Greg, it's just you seem angry?" John questioned whilst eyeing him cautiously.

"Everything's fine. Now let's go," Lestrade retorted abruptly.

"Ok," John said. "But you know if you ever want to talk, I'm always here."

"Oh, right, thanks John, I'll bear that in mind," Lestrade replied, slightly taken aback by John's offer.

"I mean it," John confirmed.

"I'm sure you do, and if ever I need to talk someone, you'll be the first one I'll go to," Lestrade lied; he wasn't really one for discussing his feelings. "Anyway, lets' get you back home, shall we?"

"Must you drive so quickly?" Sherlock asked, antagonising Lestrade.

"What do you mean? You're always trying to speed everything up usually. 'Hurry up and get me case, Lestrade', 'hurry up and get away from my crime scene, Anderson', 'hurry up and make me a sandwich, John', 'hurry up and come and fetch me, Lestrade'," he mocked bitterly.

"Yes, it is true that I prefer a fast-paced approach to life, but not so fast-paced that I could end up wrapped around a lamp post," Sherlock explained, to which Lestrade scoffed. "I sense that you're still harbouring some resentment about providing us with a lift this evening."

"Nope, no resentment, none at all, I'm fine," Lestrade insisted as he gripped the steering wheel with brute force.

"Sorry to drag you away from whatever it was you were doing tonight, I really do appreciate the lift, mate," John told him gratefully.

"I know, it's fine," Lestrade said. "It was just bad-timing that's all."

"Actually it was very good-timing if you ask me," Sherlock interpolated.

"Except nobody did ask you," John muttered from the back seat.

"If I hadn't had called you away from that woman…" Sherlock began.

"Her name is Carol," Lestrade cut in.

"Who's Carol?" Molly whispered to John.

"No idea, I was about to ask you the same thing," he replied.

"It doesn't matter. You should be thankful that I interrupted, as if it weren't for me she'd have dug her claws even deeper into you and by this time next year she'd have chewed you up and spat you out and you'd be penniless and alone," Sherlock told him unashamedly bluntly.

"You can't say stuff like that, Sherlock, you don't know that is going to happen," Lestrade spat out.

"Oh come one, look at the size of her house, the model of her car, the quality of her furnishings, the labels on her clothes. Then look at her salary. Plus, she's got two kids to support. It doesn't add up," Sherlock told him.

"Oh, I don't know, maybe she recently came into some inheritance or something," Lestrade suggested.

"Nope, all her relatives are estranged; they all disapprove of her gold-digging nature. They prefer love over money, unlike dear old Carol herself."

"How do you even know this? I know you're good at deduction, but even you need to have met the person in order to have deduced their life story," Lestrade said.

"I have seen her," Sherlock revealed.

"When?"

"Recently, at a glance, which was all I needed," Sherlock told him, with a smile.

"Right, well whatever, I'm not just going to dump someone as out of my league as Carol just based upon your instincts and dodgy impression of her," Lestrade told him defiantly as he pulled up in front of 221B Baker Street.

"Ok then," Sherlock seemingly surrendered and went to open his door, but before he got out, her added: "But maybe you might want to ask yourself why someone so out of league seems to be interested in you."

"Oh, just go," Lestrade ordered.

"I'm going, rest assured, but I'll see you later on today at the school," Sherlock announced.

"What why?" Lestrade inquired, confused.

"For the talk that you wanted me to do for the sixth formers," Sherlock explained.

"That was meant to be today, and besides, that was just an excuse for Moriarty to get you there."

"I know, but I'd already prepared a talk and it would be such a shame for no-one to ever hear it," Sherlock enlightened.

"Well, ok, then, I mean I could tell them that you've rearranged your visit to this afternoon I suppose, if you really want to do it," Lestrade offered.

"I do," Sherlock confirmed eagerly.

"Right, well I'll meet you in the foyer at lunchtime, you can make your own way there," Lestrade said before speeding away into the distance.

The students began filing into the assembly hall and chatting noisily as they took their seats. Lestrade leaned over to Sherlock and whispered: "Now be careful what you say Sherlock; they are kids, remember. Just try not to be too much like yourself and don't freak them out, please."

"I shall act upon your advice, as always," Sherlock said dryly.

At this point a tall, dark haired man dressed in a navy blue suit with piercing azure eyes stood up and began addressing the students. "Good afternoon Year 13, you might be wondering why I've called you into assembly on a Friday, and it's because we have some special guests here with us today. We've got Detective Inspector Lestrade form the Metropolitan Police. And a man you might be familiar with, the only Consulting Detective in the world, Mr Sherlock Holmes." This prompted a loud applause from the audience.

"And his assistant, Mr John Watson," the teacher added, gesturing towards John as the adolescents remained silent. "Ok then, Mr Holmes, the floor is all yours."

Sherlock rose from his chair and moved to the front of the hall. "Hello. I'm here to talk to you all about the Science of Deduction, and I thought what better way to do so than to demonstrate on one of you. So, who wants to volunteer?"

On hearing this, every student raised a hand eagerly in an attempt to catch Sherlock's attention, except for Leah Conrad that was, who was sat in the very front row, staring at him intently. "How about you?" he said pointing towards her. Leah ignored Sherlock's request and remained seated defiantly, so Sherlock strode towards her, grabbed her hand and pulled her to the front.

"For instance, here we have Leah Conrad, whose name is written neatly on the Maths exercise book I can see coming out of her bag. So Leah, I notice you have obvious dark circles under your eyes, which indicate that you have trouble sleeping. This is really expected as insomnia is a problem often common in young protégées. And how do I know you are a genius? Well, it's the way everyone acts when they are around you. Your teachers look at you in awe, almost in admiration of you. Your fellow peers however, sighed when I called you up to the front, suggesting they dislike you and your tendency to always get all the attention as a result of your intelligence."

"Sherlock," Lestrade tried to intervene, but was batted away swiftly.

"Your hands are well worn, indicating exposure to a variety of different chemicals without gloves. Today, your hands are stained with a rusty-brown substance, which you have not bothered to wash off, indicating it is only a mild irritant, most probably iodine, which is a common indicator used to test for starch. The indents on the side of your face show that you have been wearing safety goggles recently, so you have just come from doing a practical experiment. The mark on your right thumb suggests you have been using a syringe, the fact that the indent is quite pronounced still implies that you had trouble squeezing the contents out so it must have been some sort of viscous liquid, sodium alginate perhaps, which you had to force out the nozzle attached to the syringe to make enzyme beads. I can tell you were wearing a lab coat which was too big for you, as there are splashes of liquid on your top which have almost dried now, indicating that it occurred midway through the practical. Therefore it is probably calcium chloride from when you were dropping the beads into the solution to set. Which enzyme did you immobilise though? Well that's easy, I know that from the iodine stains you were testing for starch and the enzyme that catalyses the hydrolysis of starch is of course amylase. So the practical you have just been doing in double biology was testing the effect of immobilisation of amylase. How do I know it was a double lesson? Using the iodine is the final stage of the experiment so you must have finished it and such an investigation takes time, plus you're a perfectionist so you want to get it right, therefore it would have taken you at least two hours to complete." Sherlock relayed barely pausing for a breath. "Now, in regard to your character, your many split end show that you usually pay little attention to your hair as you care more about your work than your appearance. However it is clear that you have tried to style it recently, which is interesting."

"Ok Sherlock, I think that's enough now, don't you?" Lestrade attempted to stop Sherlock before he took his deduction any further. His efforts though were futile, as Sherlock only proceeded to speak a little louder.

Meanwhile everyone else in the room was completely silent; totally entranced by Sherlock, eager to hear what he deduced next.

"Today you're wearing a coat of foundation, some blush, and mascara. The rash on your cheek indicates that you've had a reaction to the make-up though, so you are not used to it, and thus you must have taken to applying it only recently, so I imagine you must be attempting to impress someone. You keep rubbing the bracelet on your wrist, drawing constant attention to it, indicating it is very dear to you, and therefore most probably a gift. It could be a gift from a relative but I'd say more likely from a lover, based on the fact that you've gone to the trouble of wearing clothes today that specifically compliment the blue gems in the bracelet. It is obviously much too expensive to have been bought by someone around your own age; therefore it was evidently a gift from someone older. It's still in perfect condition so I'd say it was bought fairly recently, maybe in the past few days. But you haven't taken it off since, shown by the stiffness of the clasp, which I discovered when pulling you up to the front here. Oh yes, I'd say you are absolutely head over heels in love with him. A young girl like you is easily romanticised, you are naïve and easily led. You believe everything he says, but little do you know that his feelings aren't really reciprocated, he's only telling you what you want to hear so he can exploit your intelligence and your naivety to gain revenge on a certain enemy of his. You're nothing more than one of the many pawns in his chess game. But you don't have to be Leah; if you're strong enough you can end it now, before it goes too far."

"Right, well thanks for that Mr Holmes. But I really must be getting to maths now, we've got binomial expansion, my favourite," Leah announced, straightforwardly.

"Oh, I see," Sherlock realised. "You ought to be careful; binomial expansion can be dangerous you know."

"I know. That's why enjoy it so much." Leah told him with a smile, before turning to leave the assembly hall.

"What the hell was that back there?" Lestrade hissed at Sherlock as they left the school auditorium.

"As I said before I began, it was merely a demonstration of the Science of Deduction," Sherlock told him matter-of-factly.

"That was a not a demonstration, that was a bloody display, and a cruel one too. That girl is only 18 years old and you tore her to shreds in front of her classmates. Not only that, she's the one student in that room who has heavy involvement in our current case. That was unprofessional, and completely unacceptable," Lestrade ripped into Sherlock. "I knew I should never have trusted you to actually behave for once."

"And to be fair, it was hardly a deduction, seeing as you were already aware of many of those things about her," John quipped in with, as he hobbled along behind Lestrade and Sherlock who were racing on ahead of him.

Sherlock threw a quick but piercing glare in John's direction before returning his attention back to Lestrade. "As you said, she's 18, which makes her an adult, and thus not as vulnerable as you're making out. And besides, she's stronger and smarter than you think. Much, much smarter, in fact. I needed to demonstrate on her as a way of warning her about Moriarty and what he's doing," Sherlock explained.

"Which is why you were so eager to do the talk," Lestrade stated, understanding at last.

Sherlock nodded.

"Did you really have to do it in a middle of an assembly, though?" John asked.

"It would be too obvious if I cornered her on her own, and besides the only time Moriarty isn't tailing her is in assembly when he has to take registration for his own tutor group. Twenty minutes is only a short window, so he thinks that it's harmless. But it was just enough time for me," Sherlock continued.

"Surely it wasn't as she didn't seem to take any notice of you at all," Lestrade argued.

"Oh she took notice, but she already knew. She's known what he's been up to since practically from the beginning. Clever girl indeed."

"What?" John asked incredulously.

"How could she possibly know?" Lestrade added.

"She worked it out. She's the one that's been playing him. And now she's got a plan, some sort of sting operation I suspect," Sherlock explained.

"Plan? What sort of plan?" Lestrade inquired, still desperately trying to digest what he was being told.

"She didn't reveal the details," Sherlock began.

"She didn't reveal anything," John interjected. "We were in there too, you know."

"Yes, but you just weren't listening," Sherlock stated.

"Well go on then, tell us you know she's got some master plan up he sleeve then," John said.

"The theorem, John!" Sherlock boomed excitedly.

"What theorem?" John inquired further as he struggled to open the door, which Sherlock had let shut behind him as he left the school.

"Oh, for God's Sake, Sherlock, get on with it and give us the whole explanation. I haven't got all day," Lestrade shot in.

"Moriarty wrote A Treatise on the Binomial Theorem," Sherlock revealed.

"Oh, of course he did," Lestrade commented as he rolled his eyes.

"Which is why Leah told me she was going to do binomial expansion this afternoon," Sherlock continued.

"Probably a ridiculous question, but how can you be sure that she wasn't just going to do binomial expansion?" John asked.

"You're right, it is a ridiculous question," Sherlock replied. "She's doing her A-Levels currently, and binomial expansion is too simple a topic for A2 Maths; she would have mostly likely studied it last year for her AS exams."

"Right, I see," John said, raising his eyebrows slightly.

"It was a coded way of telling me that she knows the real identity of her Chemistry teacher," Sherlock told them.

"And that's she on to him," John added.

"Exactly!" Sherlock exclaimed, turning round dramatically to face John as he did so.

"So we're just going to stand back and let an 18 year-old school girl take on the world's greatest criminal mastermind based on the fact that she lied to you about what she was doing in her Maths lesson," Lestrade clarified sceptically.

"I really wish you would stop calling him that." Sherlock said, pouting.

"I'm not really sure I'm comfortable with just letting her get on with it," Lestrade told him.

"Why not? She's already proved how perfectly capable she is," Sherlock argued defensively.

"Maybe, but we don't even know what she's going to do; she might be putting herself in danger," John worried, still struggling to keep up with the conversation as well as with the pace of the pair who were striding ahead.

"And if she wants to do that, then it is entirely her decision. Just before she left I warned her, and you heard her say that she loves such danger," Sherlock reminded them of the final exchange between himself and Leah during the assembly.

"Hmmm, so she enjoys the thrill of the chase. Sounds familiar," John murmured.

"I'm not sure about this, it doesn't seem right," Lestrade voiced his concerns.

"You trust me don't you?" Sherlock turned to face Lestrade as he asked the question.

"Well, yes," he replied.

"And you know I'll get the job done?" Sherlock prompted.

"Yeah, I mean you usually do," Lestrade said.

"I always get the job done," Sherlock corrected him. "Therefore, you should trust Leah too."

"But she's not you, Sherlock." Lestrade stated with a heavy sigh.

"Yes, but you heard Moriarty say it yourself that she's pretty close in comparison."

"But if it doesn't work out…" Lestrade started.

"Then I will of course succumb to Moriarty's demands," Sherlock confirmed.

"Right, well good," Lestrade said with a nod. "I'll see you back at the station in about an hour or so then to discuss matters further."

"Yes ok," John established.

"But in the meantime enjoy your lunchtime date," Sherlock told him, demonstrating his deducting skills once again.

Lestrade simply shook his head in response as he walked away from Sherlock,-who had just waved down a cab in the street-and back towards the school entrance.

A/N: Well that was fun wasn't it? Until next time…