Disclaimer: I don't own these characters, Moffat/Gatiss and Conan Doyle do. Please review!
Mary Sue Morstan skipped down the streets of London. "Gee whiz, what a lovely day! The sun is shining, and the birds are singing! What could be better?"
Mary Sue was so happy she didn't watch where she was skipping and bumped into John Watson, knocking him over. Mary Sue helped John up because she was such a nice person.
"Gosh, you're pretty," John said. "What's your name?"
"Mary Sue," she said, with a smile so bright John had to wear shades.
"Mary Sue, will you go out with me?" John asked.
"Of course!"
Mary and John fell in love right at their first date. John was over the moon.
He said, "I can tell you're in love with me because your pulse is elevated and your pupils are dilated."
Mary Sue thought that was totally romantic. She definitely did not think it was a strange, creepy comment that a fanfiction author would have thrown in because all fanfiction authors must reference "A Scandal In Belgravia" whenever two characters fall in love. Then John took her to 221B to meet Sherlock. Sherlock was bored, so he deduced Mary.
"I can see that you're a primary school teacher because you're too dull to do anything else, you're thirty-three years old and spend exorbitant amounts of money on wrinkle creams so that you will look twenty-four, you sleep with a plushie, and your biological clock, as they call it, is ticking and you would like to marry John and have children as soon as possible."
"Why, that's absolutely correct!" Mary Sue beamed. She was so proud to have been deduced by Sherlock Holmes!
John dashed out of the room and returned a moment later with a small box. "Mary Sue, I know we've only known each other a day, but I feel like we are soul mates and should be together forever. Will you do me the honour of being my wife?"
"Yes, John!"
Mary Sue and John were married that Saturday and the ceremony was everything Mary Sue had dreamed of since she was a little girl, despite the fact that they only had four days to plan it. Everybody who knew Mary Sue pitched in and contributed something for the wedding because they loved her. Sherlock was the best man and gave a toast at the reception and was a perfect gentleman the entire time because he respected Mary Sue so much. Mycroft came to their wedding and Mary Sue taught him to dance the Macarena!
After the honeymoon, Mary Sue moved into 221B with Sherlock and John because she understood that Sherlock and John were the super-bestest best friends ever and they could never ever be separated, not even by John's wife. (But they were not a couple, although even if they were, she wouldn't have been bothered because she was open-minded and cool like that.) She made them both tea and helped them solve their cases and taught Mrs. Hudson a new recipe for scones. She helped Molly Hooper get a date with a pilot and helped Mycroft and Lestrade to open up about their true feelings for each other. (Because Mycroft and Lestrade totally do love each other passionately, even though they've never appeared on camera together. Totally. All-encompassingly.) She even got Sally Donovan to stop calling Sherlock a freak! Anderson was the only one who didn't like Mary Sue. (Anderson's greatest fear is that nobody cares what he thinks. Mary Sue doesn't have the heart to tell him it's true.)
Then one day something awful happened! Moriarty came back and kidnapped John, Sherlock, and Mary Sue!
Sherlock protested, "How can you be alive? The bullet went through your brainstem!"
Moriarty rolled his eyes. "Sherlock, who cares how I eat or breathe or other science facts? This is just a fanfiction! You really should relax."
Moriarty took them to his underground lair and they were all very frightened, even John the calm ex-army doctor, but Mary Sue saved the day by knocking all of Moriarty's henchmen out with a boot to the head! (She had a black belt in Ti Kwan Leep.) Mary Sue called Scotland Yard and Lestrade came to arrest Moriarty.
When Lestrade put the handcuffs on Moriarty, Mary Sue said, "Being mean is lame! You should be nice, because that's cool!"
Moriarty said, "You're absolutely right! I repent of my evil deeds! Lestrade, please take me to jail so that I might pay my debt to society!"
John, Sherlock, and Mary Sue were all about to go back to 221B when Mary Sue shouted, "Get down!"
She knocked John and Sherlock over just in time to prevent them from being shot by Sebastian Moran! (Because she notices things that Sherlock does not. Again, she's cool like that.) The bullet hit Mary in the chest, but luckily she had a gun in her purse and she shot Moran before she died in John and Sherlock's arms. John and Sherlock were both crying like little girls, because that's exactly what you'd expect from an ex-soldier and a sociopath, right? Her birthday is now a national holiday in London, and every year everyone spends the day remembering her kindness and her beauty. (Except Anderson, who stays home and plays with his dinosaurs.)
A/N: This story was inspired by "A Trekkie's Tale" by Paula Smith. (Google it.) Happy April Fool's Day! :) Moriarty's first line is taken from the Mystery Science Theater 3000 theme song. Mary Sue's comment to Moriarty is shamelessly stolen from "The Big Bang Theory."
PS – I wrote this when I had a sick day and was under the influence of cough syrup. If it sucks, blame the cough syrup.
PPS – The main ingredient in my cough syrup is Jack Daniel's. Alcohol is bad, m'kay?