John returned to 221B Baker Street after Mary Sue's death. He spent most of his days moping, and Sherlock was totally supportive of his moping, except for the times when he dragged John out on a case. Which was pretty much any time he got a case, which was pretty much any time he was home more than half a second. Anderson and the fangirls had been stalking Sherlock since his return, and he was totally thrilled to help them find their lost kitties and get the boys they liked to notice them (or in Anderson's case, to get Sally Donovan to give him the time of day again). Anyway, Sherlock didn't think these cases were ridiculous and was really happy to take them, because somehow a two-year crusade to torture and kill all of Moriarty's men had turned him into a gigantic teddy bear.
What was I saying? Right. John was moping all the time, even when Sherlock dragged him along on cases. And then one day someone climbed up the 17 steps and knocked on the door of 221B. (All fanfic authors are required to mention the number of steps at least once in every story.) John had to get the door himself because Sherlock was off at the morgue snogging Molly. (In Molly's dreams, that is. In reality, Sherlock had found another pig to harpoon and Molly was doing his laundry. If you kids want to attach a second meaning to "doing his laundry," go right ahead. Since this fic is rated K, Molly will just be over here with the stain remover. Meanwhile, we're getting off track. Back to the knock at the door.)
John opened the door and was gobsmacked at what he saw. "M-Mary Sue?" "Yes, John! I'm back, and I've missed you so!" Mary Sue cried and leaped into John's arms. John started bawling and Mary Sue started bawling, and pretty soon there was a big puddle of tears at their feet. (Gross. But Mary Sue will clean it up because she doesn't want to trouble Mrs. Hudson.)
John sniffled, "I can't believe it's really you! The bullet went through your aorta!"
"But John, it was only a flesh wound!" Mary Sue cooed. "A very nice man named Charles nursed me back to health, and after two years I'm finally home!"
John didn't get at all suspicious when heard that, because he really is just a dumbass. Anyway, since his wife had returned, they decided to go out on a date. At the fancy restaurant, the waiter looked sort of familiar, but John couldn't figure it out. It wasn't until dessert that it finally dawned on him…
"Mycroft? What the hell are you doing here?"
"Just saving you from yourself, John," Mycroft said, and tackled John just in time for a bullet to whiz past his ear.
Because he's such a man of action, Mycroft got up without wiping the wine off of his shirt and proceeded to whip out an Uzi. He was about to mow down John's assailant when Mary Sue took out Mycroft and the assailant with one kick! (She has a black belt in Hip-Hopkido and she's opposed to guns.)
Mary Sue yanked the ski mask off of the man who tried to shoot John and revealed Charles Augustus Magnussen!
"Doesn't anyone just stay dead anymore?" John groaned.
Magnussen chided, "Now, now, John, don't be upset. I came here about your wife's little secret."
Mary Sue replied in a sing-song voice, "Secrets, secrets, are no fun. You are hurting everyone."
Magnussen flicked Mary Sue's face. "Mrs. Watson, you've been a naughty girl, haven't you?"
With earnest sincerity, Mary Sue said, "Why, no, Mr. Magnussen! Gosh, I've never done anything wrong!"
"Really?" Magnussen cocked his head. "Never cheated on a test?"
"No, sir!" Mary Sue said indignantly. "It's wrong to get a grade you didn't earn!"
"Never skipped school when you weren't ill?"
"Certainly not! It's totally cool to stay in school!" Magnussen frowned. Somehow, the expert blackmailer didn't know what an extremely good person Mary Sue was!
"Never stained a borrowed item of clothing and lied about it?"
Mary Sue gasped, "Definitely not! If I accidentally spilled something on my friend's clothes I would pay for the cleaning and write the owner a letter of apology! And speaking of accidents, Mrs. Hudson told me to tell you that you're not allowed at Baker Street anymore! She thinks you're frightfully ill-mannered."
"I assure you, I have no desire to return to your disgusting hovel," Magnussen snarled. "Surely you've done something wrong, Mrs. Watson. Have you ever littered?"
"Good gracious, no!"
The blackmailer raged, "Have you ever squished a bug?"
She huffed, "Of course not! Insects are very important to the ecosystem, and they never did anything to me!"
"Good God. You must be the most boring woman on the planet!"
Magnussen threw up his hands in exasperation. "Fine, let's move on to John. We all know that Miss Goody-Goody over here isn't really the one you love. She's just here to distract everybody from –"
"ME!" Everyone turned around as the woman formerly known as A.G.R.A. crawled out from beneath an adjacent table carrying a shotgun.
Magnussen shrugged. "Not the person I was thinking of, but I'll take it!"
"Shut it, wanker," she snapped, knocking him over with the shotgun barrel.
"Who are you?" Mary Sue looked at her, bewildered.
"I'm Mary Watson, you twit! What are you doing with my husband?" She demanded.
"But that's not possible! He's my husband!" Mary Sue protested.
"I'm afraid it is, and he isn't," Mycroft said evenly. "You are legally dead, Mary Sue. If you were to challenge her in court, you wouldn't have a leg to stand on."
"But John loves me! Don't you, John?" Mary Sue pleaded.
John took a moment to size up both Marys. "There's only one fair way to settle this. The two of you have to fight."
Mycroft rolled his eyes. "Oh for God's sake! That's really the only thing you could think of?"
"No one asked you, Mycroft!" John barked. "Go home and snog Lestrade or something!" Mycroft left, grumbling that at least John hadn't suggested Molly Hooper.
Mary Sue began to protest that she could never be in a fight, but before she finished her sentence, the other Mary knocked her out with one punch.
"I have to admit, that was pretty sexy," John said. The two of them took each other's hands and made for the door.
Meanwhile, Mycroft's people arrested Magnussen and decided that the only appropriate punishment for him was a lifetime in a cell with Mary Sue. Everyone lived happily ever after – including Magnussen, because after a few weeks in the cell he went deaf and could no longer hear anything Mary Sue said.
A/N: As with the prior chapter, this is what happens when I get sick. Luckily for all of you, I have a pretty robust immune system. :) Happy April Fool's Day!