(This is like "6 Characters in Search of an Author" crossed with "Sophie's World" — Fourth Wall Destruction Extravaganza)
Moftiss kills Molly off in a horrendous way because she humanises Sherlock and they say they want Sherlock completely sociopathic for Series 4 and 5. Sherlock the character goes rogue. He refuses to do anything the writers make him do — he acts out of character no matter what and who they put in his way and uses objects in his world to demand that the writers do something (ANYTHING!) to bring his Molly back or he will completely disappear and never return. Sherlock does all this in the script. Sherlock is somehow able to change the content of the written original scripts because only one "master copy" is made before recopying and distribution to cast and crew. The writers notice this but only after Sherlock gets his Molly back.
Plot twist: Sherlock has other things up his sleeve so he can prevent the writers taking anyone he loves away from him. What that is, is up to you.

Molly was dead. Molly had died. Sherlock tossed this thought over and over in his head. How could they take his Molly away? His pathologist. He wasn't going to take this lying down. He'd done a lot of things he didn't want to do because the writers somehow thought that their judgement was better than his. It's not like they'd made him do anything he hated doing (well, there was the whole stag night thing, but that'd been fun, at least, though incredibly embarrassing.) But, this…. This he would not stand for. You can't take his John away, you can't take his Mrs. Hudson away, his brother was necessary and so was Lestrade…. but taking his Molly away was definitely, definitely the worst idea they'd ever had.
"Sherlock, you alright?" John was playing with what was eventually going to be a newspaper, hoping it would light up with writing soon… it'd been awhile and it had not. "Hiatus." John snorted under his breath.
"I'm fine, John." Sherlock brushed him off and lit a cigarette.
"Why are you smoking? You know they only let you have a smoke a few times a series."Sherlock scoffed at this, fluttering around his flat in his dressing gown.
"Well, I think the writers are under the influence of something far more potent than a damn cigarette, so they can take a flying leap, thank you very much."
"What are you on about?" Intentionally and dramatically, Sherlock placed both hands on either arm of Johns chair and exclaimed through gritted teeth.
"THEY THREW ME OFF A BUILDING, SHOT ME AND NOW THEY TOOK MY DAMN MOLLY!"
"ok." With a growl, Sherlock returned to his pacing.
"I need my Molly, John." He turned to his friend with a look of desperation and something akin to insanity.
"I can see that." The doctor noted.
"Why would they kill Molly? What did she do to them? Laugh at one of their jokes too loud? Say something too nice to someone? Not smack me hard enough? I mean, really." He finished pacing for a moment and tossed him self onto the couch with a great puff of dust. Laying on his back he inhaled the cigarette in long, extended breaths and slowly exhaled, lazily playing with the smoke with his fingers. This seemed to call him down. "I need her back John, we have got to get her back." He closed his eyes, savoring an inhale.
"Listen this isn't Doctor Who or Supernatural, when a character's killed off they stay dead."
"Irene's still alive." Sherlock retorted, matter of factly.
"WHAT THE FUCK! YOU IRENE AND MORIARTY! ARE THEY HIGH?!"
"I think so." Sherlock shrugged.
"Well, alright then, if we can get Molly back, then we'll know how to save any other characters they needless kill off."
"We can save her how I saved Irene."
"How's that?"
"Go rogue."
"But, how do we do that?"
"We do whatever we want, I just went to the Middle East for the woman, but Molly.. Molly will be harder to get back… we'll need to show them the error of their ways."
"How do we do that?" Sherlock gave John a devious look. "No, no, whatever you're thinking is obviously not good. Not good at all and I'll no part in it."
"Well, they're probably going to take Mary next." His friend grunted and paced a circle into the floor for few seconds before relenting. He sat up and put his cigarette out in one of the ash trays they'd stolen from the palace.
"Ok, whats your plan?"
"Simple." The detective approached his friend and snatched the paper from his hand, tossing it onto the floor. "Johnlock"
"Wha—" Before he could get the word, Sherlock had pulled him into a passionate kiss. John struggled to get himself free and immediately punched Sherlock in the face. "WHAT THE FUCK IS YOUR PROBLEM?"
"That hurt." He rubbed the bruising skin on his cheek. "That wasn't very nice."
"Well, shoving your tongue down my throat was rude to say the least and bat shit crazy at best. What are you on?"
"I miss Molly." Propping his face at an angle, he gave his friend his best puppy dog eyes, even allowing them to tear a bit.
"What exactly were you and Molly doing?" With a sigh, Sherlock resumed his former position on the couch and lit another cigarette.
"Well, nothing yet, the writers won't let me shag anyone. Say I'm suppose to be sexually repressed. You can only masturbate so many times a day, John"
"A day?" John stood, aghast.
"I'M A NEARLY 40 YEAR OLD VIRGIN, FOR GOD SAKES, THEY SHOULD BE BLOODY GRATEFUL I HAVEN'T SHAGGED A HOLE IN THE SOFA!" Sherlock screamed, his face growing a bit red from the strain.
"Jesus, its that bad?" asked John.
"You have no idea." The other man groaned as he rose from the coach again.
"Alright, well, I'll let the kiss slide, but no more funny business."
"Ok." Immediately, Sherlock pulled John to him again and all the doctor could do was shorten the kiss.
"That wasn't an invitation to kiss me again, you jackass!" He swatted as his friend, who was acting beyond out of character.
"I understand, lets just wait until the new scripts start coming to make our move." Sherlock replied in as calming a tone as he could muster.
John was agreeable to this, mostly because it meant his friend wouldn't be accosting him again, but also because Sherlock may have calmed down by then.

But, he didn't.

When the script drafts began arriving, Sherlock would jump with glee. Grabbing at the papers floating from the ceiling with a pen in one hand and a devilish smile painted across his face.
"No! No! Absolutely not. Haha! Not this season, Gatiss." Scoffs, snorts, exclamations and giggles filled the room, leaving the other characters to believe, perhaps, he had finally gone completely mad. "I don't feel like doing that Moffat. Make Mycroft do it." He'd whine every once in awhile, or a "Really, Gatiss? That's not even necessary. Is that english?"
Then one day, a frightful bought of laughter disrupted the whole of their little world as an unkept Sherlock Holmes leaned out the window, naked, shouting "I DON'T TAKE SUGAR IN MY COFFEE ANYMORE!" and threw himself back onto the carpet, collapsing under the weight of his giggle fit.
"Sherlock." It was the forth time John had spoken his name, but the first time the mumbling, nude idiot paused to look up at him. "Are you alright? Some of the other characters thought you might need a shower and shave…. Mary thinks you look like Jesus… finds it unsettling." Sherlock replied with a blank, blinking stare. "Ok. Come on." He pulled his nude friend off the floor and drug him into the bath room where he ran a bath.
"Molly's done this before." The mopey taller man fiddled with his ugly beard.
"I'm sure she has…" Under his breath, he added "apparently she did a lot."
Sherlock didn't fuss, fight or move until John pulled out the razor and brought it to his face.
"NO! I do." He pointed to himself with one hand and accepted the bladed instrument with the other.
"Yeah, ok… couldn't have said that when I washed you bum, right? Maybe I should have taken a machete to it."
A little while later, as John was watching print appear on the newspapers, a jovial Sherlock ran in to join him in the living room… still naked and sopping wet.
"John! John!" The closer the crazed man got, the more defensive John got.
"You touch me naked, I will shoot you." Confused, the man stopped right up against him. They stared each other down for a moment, before Sherlock took a single finger and started playing 'not touching you', after a few, aggravating seconds, John took the mans finger and twisted it, pulling his arm behind his back. "Are you done?" He asked.
"Well, I am now!" Sherlock whined.
"Good." The former army doctor released his friend.
"Will you do me a favor, John?" Sherlock nursed the knuckle of his hurt finger by gently biting on it.
"If you put some clothing on." John demanded.
"What for?" The hand movements Sherlock had acquired as of late were erratic and big and John was nearly smacked in the face.
"Not everyone wants to see you naked, Sherlock." He informed Sherlock.
"Please, it's not me thats naked…. I'm just an idea borrowing someones likeness."
"Ok… well, than whose likeness are you borrowing?"
"Some Ben guy… weird last name… can never remember it." He waved it off to stare out the window.
"Yes, well, I'm sure he'd appreciate you putting your trousers on."
"He's done nude shows before. Had one role where he pranced around on stage naked for 15mins at the very beginning. Why should he care I'm walking around naked in my own home?"
"Fine. Just, whats the favor?"
"I need you to go set something on fire."