A/N Since in the Whoverse there are now thousands of Clara's, I couldn't help but play around with the idea that one of them is John Watson's sister in-law. I'm sure I'm not the first, but I am pretty sure no one else will take it in this direction. There's sort of hints at Clara/Doctor, and far more subtly John/Sherlock, but it's not very shippy.
I had this all planned out before seeing Day of the Doctor, and now it doesn't quite fit into the world. Sorry dear readers, you will just have to suspend your disbelief.
Chapter 1 - Clara
"The least they could have done was offer us a ride home. We did after all save them from an embezzlement charge that would have surely bankrupted the company and possibly landed them both in jail," Sherlock grumbled as he and John made their way home from Regent Park.
"Well you did out him to his fiancé/business partner at their rehearsal dinner."
"It was imperative that they be informed at once. And I need not remind you that the hiring of a Rent Boy was a key piece of evidence towards his innocence." Sherlock noticed a black cab up the street, but John stopped him before he was able to hail it.
"Sherlock," John said, in the type of tone one uses when speaking to a child, "we are only a few blocks away. Besides, the walk will do us good." Sherlock adjusted his scarf and stared directly in front of him. Insolent child, John thought without a trace of malice.
They stopped for a red light next to a small brunette. John glanced her way and then did a quick double take, "Clara?" The woman turned around, but seemed to look right through him. "It's John. John Watson. Harry's brother."
The woman still stared at him without recognition, "Sorry, I think you have me mistaken for someone else." Her eyes shot up to see the light change before taking a final look back at John, "Again, sorry about that." In the next moment she was moving quickly across the street and was soon lost to the crowds.
John stood there truly perplexed, "It was like she didn't know me."
"No, she didn't," Sherlock said, leading his bewildered friend across the street before they missed the light.
"She looked at me as if we'd never met before... I mean I know her and Harry didn't exactly end on good terms, but I've known that woman for years..."
"I doubt that," Sherlock said in his matter of fact way that tended to make people want to hit him. Such obnoxious confidence never phased John, he looked up at Sherlock and waited for an explanation. John knew he had no patience and would spell everything out given time. True to form Sherlock asked, with a hint of a smile, "How does your sister manage to acquire such young tail?"
"Tail?" John repeated, highlighting the colloquialism that sounded so unnatural when Sherlock said it.
"I mean that kind of age gap is impressive, she must have a great deal to offer."
"Age gap? My sister and Clara met in university, they are the same age, almost to the day."
"And she is your older sister?"
"You know very well she is. We're almost home, would you get to the point already."
"The point, my dear Watson, is that the woman you spoke to today was no more than 25 years old."
"She... you're right, she was..." John's expression softened as he reevaluated the exchange, never once letting his pride get in the way of the facts. "She was quite young, wasn't she?" This was one of the traits Sherlock liked best about John, that he was in no way pigheaded. So many people (particularly those Sherlock encountered in law enforcement) clung on to ideas and theories long after they had been disproven, and then for some reason begrudged the person that had set them on the right path. John always took things at face value and was perfectly happy to admit when he was wrong, "So when she looked at me like she didn't know me it was because... she didn't know me."
"She did turn around when I said 'Clara'."
"It's not exactly an uncommon name."
John shook his head in disbelief, "She's the spitting image. That is exactly how Clara looked when I first met her." Sherlock still wore his condescending smirk. "You don't believe me?"
"I believe that you believe it and I don't doubt the girl probably resembles your ex sister in-law. But the brain is constantly interpreting data and filling in pieces. I think she reminded you of Clara and that's who you saw her as." John unlocked the door to 221b Baker Street and held it open for Sherlock, "Incidentally, that is also why eye witnesses are routinely unreliable."
"Not this time. I'm telling you they looked the same," John argued as the pair ascended the stairs. "I've known that woman for more than a decade and the girl look just like- Harry?" John entered the living room and found his sister sitting on the couch with her head in her hands. She looked up at the sound of her name, revealing red, swollen eyes. On instinct John knelt down beside her, "God Harry... What's wrong?"
"It's... it's Clara," she began, her voice breaking, "she's... dead." She looked about ready to collapse in grief. John reached out for her, but before he was able to comfort her she sat up a little straighter and stared directly at Sherlock, "I'd like to employ your services Mr. Holmes. I'd like you to discover..." her false composure was breaking, "why... why she died."