Jake had been pestering John to have dinner at his place for once,instead of other way round and after 6 weeks, John finally gave in.
"Fine but don't say I didn't warn you."
"Hmmm you're worth the risk."
xoxoxoxo
John set Sherlock's tea by the microscope and sank into his armchair. "So erm, I'm having my date round tonight."
"Ending it then?"
"No!" John burst out. He saw Sherlock's face-carefully calm- and sighed. He didn't mean anything by it; Sherlock was just being Sherlock (as if that wasn't scary enough). John took a deep breath and said a bit calmer: "No I was just ...he wanted to meet you."
Sherlock's hands paused on the knobs. "Did /he/?"
John blushed down at his tea "Yeah, well, we've been dating six months so it's long over due..He's a banker but not at all stuffy. We get along quite well,actually."
"He?"
John sighed preparing himself for the worst. "Yes, .A man. Anything else? He'll be here any-"
"You're dating a man?"
"Now who's repeating himself?" John smirked.
Sherlock grumbled but not loud enough for John to hear. This was not good. John could feel his will to live slowly ebbing away. He clenched his fists tightly to prevent himself from throttling his flatmate. Sherlock was going to scare Jake off,or he was going to deduce him. Both,most he should just call it off before any real damage was done...He reached for his mobile just as the doorbell chimed. Sherlock's eyes darted to the stairs but John was up on his feet and already half way down before Sherlock could move. He made it half way down before he had a thought. He dashed up the stairs,two at time, and looked round the corner. "Take the head out of the oven will you?And be nice."
Sherlock looked after him,confusion filling his face. "When am I not my adorable self?"
John shot him a Look before heading down to let Jake in.

Sherlock crossed into the went into the kitchen and tried to ignore the voices but he couldn't help but overhear. They were at the Landing, for Pete's sake.
"Mmmm you taste strawberries."
"That'll be the jam."
"Mmmm I prefer the taste of John better."
A giggle, and quiet whispers of clothing. They were deeply by the sounds of stomped to the oven and removed the head,letting the oven door slam. He shoved the toaster off with an elbow to make room for the head, and it hit the floor with a metallic clang that could be heard throughout the flat. There was a pause and Sherlock could hear John curse.

"That would be Sherlock,sorry. He 's in a bit of a mood.I swear he 's like a bloody child. Listen,Jake ,are you sure you want to do this?"
"Yes, John. You're valuable to me."
"Says the man who collects stamps."
A giggle and a sigh then -footsteps, and John came in,red-faced, leading another man behind him. The man-Jake-smiled at Sherlock "Hello, you must be the Madman Flatmate." and proffered his hand
[40 years old,slightly ginger, banker, smooth hands, firm grip, hands soft to the touch from caressing John? NO DELETE...] John was looking at Sherlock and,catching his his eye,John gave a curt jerk of his chin. He said nothing but Sherlock understood: Not this One. Sherlock dropped his hand,resisting the urge to wipe his hand on his jeans leg. "Quite."
John wrapped an arm around Jake's waist and led him away from where Sherlock was still standing. "Let me show you the rest of the flat."

The evening passed quickly for John, but time dragged by like molasses for Sherlock; Jake didn't leave enough, even after the incidient with the camel spiders.

John and Jake spent most of the evening hiding out in the kitchen.'Took cook dinner' John said but all Sherlock heard was them and flirting and tossed around tried to focus on an experiment in the living room but dammit they were too /distracting/.

Finally he had enough of the kissing and sounds there of;Sherlock stood and stomped off to his room closing the door behind him with a didn't come out when John announced dinner was ready. He didn't even come out when he had to urinate. It wasn't that he was afraid of what he'd see. He was afraid of his were there tonight and they were unpredictable. As were his possible reactions to what was beyond his bedroom door. It wasn't that he was jealous {boring}.It was just he wasn't feeling too well and,as a result,his reactions would be...could be...NO: WOULD be unpredictable and that was , that is what Sherlock told himself but he knew all this time, all the cases, the danger which Sherlock and John both /thrived/ on John was /there/...there was boring,banker who John spent every free moment he had with. What if Jake asked John to move in? Would he? Would John leave him Sherlock just like /that/ ?Such thoughts made him physically sick and,well, if he'd admit to himself, panicked, So Sherlock worked on experiments in his room,never reemerging til his pressing bladder needed immediate relief. He opened the door-and froze.

John was wrapped around Jake on the sofa, kissing softly, their hands exploring. Sherlock felt a twinge he recognized as what jealousy ? Sherlock nearly snorted. He didn't /do/ feelings, let alone ones of such possession. He wasn't was there to be jealous of ? The caressing? was sentiment. But then again...the thought of him in Jake's place drew heat, made his skin prickle and vision waver.

Sherlock closed the door of the bathroom behind him urinated then sat there in the dark, /not/ thinking until long after he heard Jake leave and John went up to his then did Sherlock emerge.

He stood at the stairs for the longest time going over tonight-what he had seen and,most alarmingly, what he had /felt/ .He undoubtedly felt jealous over someone else /touching/ John. No one else was allowed wasn't enough he went out on dates,but bringing them here? It was torture. Sherlock hadn't felt this out of control since he was a toddler and his Father banned him from the library.

He stood in the darkness at the base of the stairs until dawn and John's alarm heard the creak of the bed-John was waking up-and headed into his room again, locking the door behind him with a click.
He was /caring/ for someone, and it made him weak, Jealous,UNPREDICTABLE=vulnerable.
Not good.

xoxo
Then it happened: A week later John didn't come when Sherlock needed him for a case.

To say Sherlock was distraught would be making light of the smoked a whole pack of cigarettes and managed to make Donovan cry and Lestrade threatened to ban him from crime scenes for a this was in the first walked home to Baker Street in a rage. He considered using again-he knew John would come running if he found out, but then again John would be very upset with him, may even hit good. John may even leave. VERY not good. Shelrock wanted John with him,HOME,where he belonged, not just for sleeping and changing clothes. He belonged here watching crap telly and making Sherlock tea. Sherlock shook his head,disgusted at himself. What had he become?
He solved the case at half past 4 the next morning but he did not get the rush he usually was the missing was the key

John.
John.
John.
Maybe even /seeing/ him would help...

xoxoxoxo
John rolled over his sleep- and nearly fell out of the bed. Sherlock stood in his door way,watching him silently. John jerked the covers over himself. He only slept in boxers and he did not want his mad flatmate to see his...bits and pieces. There are just some things flatmate don't share.
"What the HELL Sherlock?"
"I finished the case."
"You couldn't text me?"
"I did."
"Bloody Hell it's -FUCK-4 in the morning."
Sherlock frowned "I've angered you."
"No shit Sherlock!" John yelled then instantly regretted it. "Sherlock, you can kip on the sofa if you'd like."
"No,I'm returning to Baker Street. I'll call you in the morning."
John woke up the next morning not sure if that had really happened or if it was just a very irritating dream.