There were many things that made Sherlock so successful as a detective and what made him stand out among all the ordinary detectives; his willingness not to get distracted from brain and thinking by things such as sentiment, due to his lack of empathy. Selena believed him when he corrected Anderson about being a sociopath rather than a psychopath. There was so much potential for a case study there! And also, his outstanding ability to observe everything and build up a picture from what he observes. This ability came naturally to him which was what made it look so easy, but for anyone else, it would be very difficult to master. Sherlock intended to introduce Selena to this method and teach it to her to the best of his ability so that she may understand it and see how well she gets on with using the technique. He didn't expect her to be as good as he was, but if someone else could use the technique, it would be useful to him as an outside eye may find something that he missed, though he believed that was highly unlikely.

Selena entered the kitchen one morning in her penguin pyjamas to make a morning brew. Sherlock sat in his chair reading the morning newspaper that Dave stereotypically brings up to them every morning once it is pushed through the letterbox. He looked to have only got up a little earlier than Selena as he wore his blue dressing gown over his own pyjamas. "Good morning," Sherlock acknowledged her presence.

"Morning," Selena grumbled a reply. She needed a few minutes to wake up properly before she could have any chance of holding a decent conversation. "Tea?"

"Yes, please."

Selena chucked a teabag in the teapot, filled the kettle with water and switched it on to boil. John must have still been asleep, since the previous night was a late one.

"We're going out today," Sherlock announced, not looking away from the article he was reading.

"Oh? Where to? Found an interesting case?"

"Lessons."

Even the word itself made Selena groan with dread. These lessons drained her energy and in some cases made her want to pull her hair out from the stress. "What about this time? More road mapping? The language of codes? Or is it more aggression conditioning? If I had chosen to pull the trigger instead of punching him, I could have killed John!"

"Yes, but you didn't."

"That's not the point!"

"It is part of the point. It showed that you have moral principles that you go by. You wouldn't have used the weapon unless it was completely necessary and there were no other options. Besides, if you had known it was John, you wouldn't have behaved the way you did. You should know that as a psychologist; demand characteristics."

Selena sighed, not willing to get into an argument about it. "Alright, I get it. So what are we doing today?"

"Deduction."

"Ah, the interesting stuff, finally."

"Once you've eaten and got dressed we'll head out."

Selena made herself an omelette for breakfast to use up the eggs they somehow managed to accumulate, while Sherlock showered and dressed. He wouldn't have any breakfast, bent on the idea that digesting food slowed down the functioning of his brain. In some ways, Selena agreed, but the energy acquired from food was necessary to provide energy to think. She prevented themselves from getting caught up in an in depth discussion about energy transfer and cellular respiration at nine o'clock in the morning. Dave was given his breakfast after Selena ate hers which consisted mostly of chicken. Selena would rather feed him proper meat or edible remains from the previous evening's dinner than the processed stuff that came in packets and tins. His ancestors managed perfectly well that way so why shouldn't Dave be able to? Selena occupied the bathroom after Sherlock, washing and getting dressed. Once they were both clean, dressed and in some cases fed, Sherlock took Selena and Dave, who insisted on joining them a little further along Baker Street and sat outside a Starbucks despite the chill of the weather. Sherlock began explaining what they will be doing. "This looks like a good spot. Not too crowded and a few still targets; should be adequate. I'm trying to get you into the technique of observing people and things, and telling me about them just from what you observe."

"Okay...So what exactly is it that you want me to do?" Selena was just a little confused about this plan.

"Show me your current skills in deduction so that I know how we can get you to improve. You've seen what I do, go ahead."

"I've only ever seen you do it; I don't know what it is what actually goes on in that crazy brain of yours. Demo please?"

Sherlock exhaled and began scanning the surroundings for their first specimen. He then gestured behind Selena to young man sat at the table next to theirs. Selena turned her chair 90 degrees so that she may also be able to observe the man in her peripheral vision. Sherlock observed the stranger's appearance, his little ticks that made up his personality and the things that could suggest details about his life. All this occurred in a matter of seconds.

"When he ordered coffee he spoke with a Scottish accent, which obviously says he is Scottish. There's animal hair on his left arm and the front of his body; it's too straight to be human hair and definitely not his own, so the hair belongs to a cat or dog, more likely a cat since the hair is only present on his upper body where he would have been holding it. If they belonged to a dog the hair would more than likely be lower down. There's a smudge of black ink on the side of his left hand which suggests he's left handed because the ink hadn't dried while he continued to write. His leg is also shaking involuntarily which indicates stress and restlessness. He looks to be in his late teens or early twenties going by the state of his skin, and a man that age is probably at university and also going by the fact that he writes a lot at a fast pace and is under stress."

Selena looked at the man in the corner of her eye, attempting to not appear suspicious. She didn't notice all those details until Sherlock pointed them out. There is no way I could do it that fast, Selena sighed inwardly, this could be a long lesson.

"I hope that was an adequate demonstration."

Selena chuckled, "A bit more than adequate, I think."

"Okay, now you know what happens, it's your turn."

Selena felt a knot tie itself up in her stomach. There was no way she could deduce as well as Sherlock could, at least not at this point, and she was nervous about making a fool of herself or appearing stupid. The rational and adult side of her mind took over and encouraged her that it didn't matter how bad her performance was, as this was only a test run to see how she could improve if it really was awful. Selena took a deep breath, looking for someone to test her skills on, turning her chair back round to its previous position. A woman sat to her left caught her eye. Her hair was copper coloured and her skin had no imperfections, which was possibly due to the work of make-up. Selena took a few minutes to observe the woman and absorb the details about her appearance and body language. Once she was content that she gathered enough information, she breathed deeply, calming her nerves and began to describe her. "That woman," she gestured towards the red-headed female, "Erm...Her make-up was done immaculately, her clothes show off her figure well, so she's gone through a lot of effort to make herself look good, so she's probably meeting a bloke. She's slouching with her arms crossed which says that she's bored and fed up and she's constantly checking her phone so I'm guessing she's been waiting here for a while checking for any missed calls or texts, so maybe the guy stood her up."

"Good, anything else?" Sherlock encouraged Selena.

There was a long pause while Selena took a few more moments to observe more details. "She's pretty well off going by the clothes she's wearing; I'm sure I saw that jacket in a Joe Brown's catalogue a few weeks back that was over £50. And I recognise the perfume she's wearing," Selena sniffed a couple of times, taking in the scent, "My mum used to wear it, that was rather expensive too. And that's all I've got. How did I do?"

Sherlock smirked, evidently impressed, "You did well. Most people just go by what they can see, but you also paid attention to what you could smell which is a very promising start indeed. I think you just need practice since there's nothing I can actually teach you. With practise you'll get quicker which is always good for when you're at a crime scene."

Selena glowed with satisfaction at her promising performance and a sense of pride washed over her. She and Sherlock relocated to Regent's Park and passed the time by practising their skills making deductions on more difficult targets; people who were a fair distance away and those who were moving which gave Selena a time limit. She found that having less time to think made her observe everything at a quicker pace. Dave entertained himself by chewing up dead branches that had fallen from the trees. Occasionally, he'd offer one to Selena asking her to play with him only to have his request go unfulfilled. Eventually he realised that his mistress was too busy to play and instead offered his stick to Sherlock who didn't seem very busy; he wasn't pulling the concentration face that Selena does when in deep thought. Again Sherlock seemed confused about this gesture. Dave had been sat waiting patiently for five minutes when Selena stepped in and introduced Sherlock to the game involving a person, a dog and an unfortunate stick, "Basically, you pick it up and throw it." She demonstrated by taking the stick from Dave's jaws and throwing it as far as she could. Dave charged after it, his tail wagging franticly, picked it up in his jaws and loped back to Selena and Sherlock.

"I don't see what this is supposed to achieve."

"It doesn't for you, but it keeps Dave occupied and gives him exercise." Selena chuckled at how intelligent Sherlock was in contrast to his limited knowledge of keeping an animal.

"What?" Sherlock asked puzzled.

"If you're teaching me this deduction technique, I think I'll have to enlighten you about Dave here, since you're so oblivious."

"Why?"

"Think of it as me returning the favour. Besides, Dave's friendship might end up saving your life one day."

Sherlock quickly changed the topic of conversation, gesturing to a man running from one end of the park to the other. "I'd say you've got about three minutes besides he moves out of sight," Sherlock informed as he took the stick from Dave's mouth and threw it, just as Selena demonstrated.

Selena glanced quickly at the runner and began talking while thinking in order to conserve time. Her deductions processed much quicker than the previous time showing Sherlock how she had improved. It seemed that the man lived alone, had a heart condition and also came down with depression after recent family problems but tries to continue a normal life and staying healthy.

This carried on for the rest of the afternoon, Sherlock and Selena having a few little chit-chats between deductions, and Dave introducing a new game which involved both competitors holding one end of the stick and pulling as hard as they can. The sky grew darker as the sun began to set behind the horizon and their stomachs growled hungrily. Selena checked her watch for the time which was half past five. "We've been sat here all day," she remarked.

"It would seem so."

Selena rose from the bench the two of them had been sat on since this morning and stuffed her hands in her pockets as the evening chill suddenly enveloped her. Sherlock followed, accompanied by a growl of protest from his stomach, which didn't surprise Selena since he hadn't eaten anything all day. "What do you guys want for dinner?" Selena asked; the question that she asked daily that never received a proper response, "I can make a fish pie? It'll taste loads better than that pre-prepared stuff that you used to get from Tesco."

Sherlock made no verbal response but smiled at the thought of decent food, only making himself hungrier. It had been a long time since he ate a proper homemade meal until Selena arrived. The detective and his apprentice began walking home, discussing their favourite food and things they liked to make. "I might ask Mrs Hudson if we can have a veg patch in the back garden," Selena thought out loud.

"What on earth for?"

"Why do you think? To grow veg!"

"And what's wrong with buying veg?"

"Growing them is cheaper and they taste nicer. I know the difference between home grown and supermarket vegetables."

"But then you'll spend more time tending to the veg than helping me," Sherlock whinged.

Selena giggled, amused by his assumption, "No I won't, I'm sure I'll find time to help you out along with tidying up your mess, making you dinner and spending time with Dave."

"Not if I get Dave to dig them up," taunted Sherlock.

"No you won't."

"Okay, maybe I won't, but only because I can't."

"Ha! I win," Selena teased Sherlock triumphantly, remembering the war that they silently declared against each other during the taxi driver case.

"We'll see about that."

A playful and somewhat childish mood came over Selena as she gave Sherlock a friendly nudge in his right arm, disturbing his balance, despite the difference in height and weight between them, "Give it your best shot, detective Holmes," she taunted him in return as they arrived home at 221B.