Show John different figures and ask him to grade them from best to worst. To be done at random intervals during opposing personalities.
"John, what do you think about these crime scene pictures? Grade them from least gruesome to most."
John: "umm... Why am I grading crime scene pictures? Fine... One, two, three, four, five. Actually, switch three and four. Good? Good."
Matt: "What the fuck is wrong with you now? Is this for some weird booklet you're making. 'Crime Scene Fetishes' or something. Man, don't you have another case we can solve? I'm getting bored here!"
Janet: "Get those away! I don't want to see those. It's not a nice thing to show others. Give those back to the DI! In fact, give them here. I'm going out for a drink with him tonight."
Chad: "Sherlock, are you doing another test? I told you, I don't want to be part of any of your experiments. It's not nice and I don't like it. Please, put that mind to work elsewhere."
Conclusion: At different times, John acts and feels differently towards the same stimuli. Calls for further study.
Sherlock sat in his arm chair opposite of John and his employer, notebook in hand. On the phone a week ago, John and Sarah had talked nonstop to each other for over an hour. They had a lively conversation about various trivial stuff Sherlock didn't find the least bit interesting.
Now that they were face to face, there was almost an awkward silence between the two. John sat as far away from her as the couch would allow. She tried to start various conversations with him, but John's natural conversation stopping tendency kept getting in the way of having an easy flowing conversation.
Just as it seemed to be getting even too uncomfortable for Sarah, a sudden change came over John. All of the sudden, John was very social and very comfortable sliding up next to Sarah.
Conclusion: Sudden mood swings. Very interchangeable.
Sherlock looked out of their upper-story window to the skip below. He saw John with another woman.
She was practically falling all over John (as other things were falling out of get dress); it was despicable. For the past half hour, they had been on the stoop talking, flirting, god knows what.
Since John's life now included Sherlock, he had been opening up to more people, but Sherlock felt that this was a little too open. John was his interesting subject. What was with all these women coming out of the woodwork's? They were getting in the way of Sherlock's time with John.
Sherlock saw the woman press herself into John's arms, trying to cling to him in an overly seductive tactic to bed him. Sherlock stiffened. How dare someone else touch John in such a way. He stomped down the stairs to the front door. He was about to pull open the door when to confront this women when he heard John's voice.
"L-look. Umm... I have a long day tomorrow and I'm not..."
"What's wrong?" she pout-whined. "Don't you want me...in your bed...with you." Sherlock wanted to gag at her attempt at seductiveness.
"No, no really..."
Sherlock opened the door to John gently trying to push the overbearing woman off.
"John, you're home," he said, trying for a fake cheeriness. "Would you please come up and help me with an experiment?"
"Oh, you have a roommate," she said stepping away from John.
"Yeah, sorry. I have to go-" John said quickly before Sherlock tugged him inside and shut the door on her face.
"Thank you," John (and all his personalities) said in unison, giving Sherlock a genuinely sincere smile.
Sherlock followed John upstairs; privately smiling and blushing as he ascended.
Conclusion: Don't let John fall into any woman's clutches. He's impressionable, innocent, and a bit naive.
Go through John's room when he's not home. [though it's not actually an experiment.]
Sherlock walked upstairs to John's bedroom an hour after John went to work. He opened the door and was confused at what he saw.
Sherlock thought maybe to find one of two things: a military clean room or a messy I'm-a-doctor-and-have-to-leave-quickly room. Instead, he found the room divided into four separate parts that coincided in the middle where the bed lie.
'Very interesting,' Sherlock thought himself.
He started on one side of the room and quickly looked around all of the separate areas. Other than the vastly contrasting taste, Sherlock only found one anomaly. Pictures- all the picture subtitles were all wrong. They were consistent in their own separate spaces; they said a different name of someone who wasn't there, and always forgot John's name. Chad? Janet? Matt? These were leads, but he didn't know how they connected.
Conclusion: John leads different lives? Need more information.
Before Sherlock left John's room, something caught his eye. He walked over a picture that was covered with a cleaning rag. He picked up the photo and took off the cleaning rag before turning it over to see the back.
"John and Sherlock," he read. He turned the picture over to see the front and smiled softly at the picture of the two discussing a corpse at the crime scene. He slightly chuckled before wondering why John would have such a picture. Is this what friends do? He felt something warm settle in his chest.
Maybe there was something to this thing called friendship.
Conclusion: John Watson considers Sherlock Holmes a friend.
Sherlock tapped the eraser of his pencil on his bottom lip. He smirked and continued to write.
Conclusion: And vice versa. Sherlock Holmes now has a friend.
Sherlock ran down the stairs leading to the subway; following the thief who had the only clue to finding where a multimillion dollar antique was going to be sold on the black market.
Behind him, John took a wrong turn and headed east- opposite of Sherlock and their subject heading west. Sherlock sighed harshly; there was nothing he could do about it now.
Sherlock intercepted the suspect at the bottom of the stairs; scuffling with him for a while before the thief brought out a knife and swung it wildly at Sherlock. Sherlock tried to block all the stabs the suspect threw at him. Just as Sherlock thought he had the upper hand, the suspect threw a right hook, connecting it with Sherlock's jaw. Sherlock stumbled back towards the edge of the platform and grabbed the air desperately for purchase. He saw the headlights of an approaching train in the distance, knowing what his thief was thinking. Without disappointment, the thief quickly approached Sherlock, arms straight out, to give him that last lethal push.
Out of nowhere, Matt tackled the man to the floor, clipping Sherlock's shoulder as he passed. Sherlock tumbled down 10 feet to the tracks below.
John gasped as he saw Sherlock fall. He saw uniforms running towards him in the distance. When he decided they were close enough to catch him if he ran, he jumped off the man and quickly ran to the side of the tracks.
'Come on, John,' Matt said, swinging his leg over the side. 'We have to go save the crazy bastard.'
Matt let go of the side of the platform. He quickly ran over to the unconscious Sherlock; John becoming more wary of the approaching train. Chad quickly looked over him to see if he was in any danger if spinal cord injury if he moved him wrong. Finding none, he hoisted Sherlock over his shoulders and carried him to safety.
Now that they were out of immediate danger, Janet medically checked Sherlock over before deciding that Sherlock's only injury was from a bump from the fall. John let out a huge sigh of relief and wrapped his arms around Sherlock's skinny frame.
"John, stop crying. It's just a bump," Sherlock said, sounding bored. "And where were you? Only because you are you, I'm giving you the benefit of the doubt."
John sniffled and chuckled. "I thought you had the suspect, so... when I found out where exactly they were hiding the antique, I had to grab it and then decided to run around to try to intercept our thief."
"You found the antique?" Sherlock asked, eyebrows raised and impressed.
"Yeah. They hid it where they usually have the fake art here; though, the suspect is probably the most important to you."
"I'm mildly impressed, John."
"Really?" he asked shocked.
John beamed and wrapped his arms around Sherlock to hug him.
"I'm glad you're okay, Sherlock."
Sherlock was confused by the amount of sentiments that John was showing towards him and the feeling he felt throughout his chest. He wasn't used to it; having a friend worry about him so much. He smiled softly despite it, though. Maybe there was something to them.
He saw the DI and his squad start to approach them and gave John a rough shove back.
"Professional standard, John," he said while clearing his throat and blushing.
John shot him a confused look before slightly chuckling.
"Well, if you're going to be like that, then you're getting checked out by the ambulance staff for that bump on your head."
John laughed harder at Sherlock's face as he personally escorted him there.