Recommended (of course, it's always recommended) that you read "A Long way to Holmes", but not required. Just know that Isabelle dies at the end of it otherwise the end of this story won't make much sense.

"EXCUSE ME?!"

"Miss Long! Please, keep your voice down!" Mycroft Holmes put two large hands up in some poor attempt at placating the suddenly very distraught woman that had just stormed dangerously towards him.
Isabelle shook her head vehemently, "I will do no such thing Mr. Holmes, I am… I- I cannot believe that what you have just said could possibly be true!"
Sherlock Holmes stood in the corner of the room looking startled, having not heard the lady's approach he had felt free to speak of a certain "bet" he and his brother had going on. He should have noticed her presence in the doorway.
Isabelle had to fight the urge to pull at her hair, neatly coiled into a passing state of acceptable.
"Miss Long these walls may be thick but not so thick that the patrons of this club might not hear you shout," Mycroft continued.
"I'm afraid at this moment Mr. Holmes that I do not care!" Isabelle informed him just as loudly, "Let them brood over a woman within their club, and silently complain over the register of her voice. I promise you I will not mind! You cannot be serious about this-this ghastly, horrible… How long did you say?"
Sherlock cleared his throat about to speak but Isabelle pointedly ignored him.

"How long did you say your life was to last?"

Mycroft cleared his throat, feeling rather like a chastised child. Isabelle did have the power within her to control a room even one filled with the two brightest minds in England.
"Two years three months was the most recent estimate," he said after a long pause filled with her piercing hazel eyed stare.
"Two years and three months' time Mr. Holmes…" Isabelle's freckled cheeks reddened as she continued her tirade, "How could you do this to yourself? Or to the many people relying upon you?"

"Perhaps I should leave." Sherlock interrupted in that deep rumble of his, making a beeline for the door. Isabelle scoffed which made her face redden more, unused to confrontation especially spurred on by she herself, "You are just terrible sir if not more so, urging him on as if he means so little," she said and he stopped his escape, "Just one more pudding, or two or six! Perhaps we can get his life down to just one month?" Her hand fluttered to her mouth, her eyes becoming watery. Oh God.
Both brothers discomfited with her emotional display, shifted uneasily in their places.

Mycroft let his hands rest upon his stomach, his mouth set in a grim line. He was unsure with how to calm the woman down. He should not have given her access to the Diogenes that would have saved him the trouble! But the dear woman had requested his help (They'd met many, many years ago and she'd read about him in John's stories), and so he given it. Mycroft had relied on the fact that he could not be swayed by anyone, yet he'd somehow been taken in by her sweet demeanor and odd sense of humor as well as the way she smiled…
Isabelle had started to come by even after the problem had been resolved (she held a secretarial position for a colleague of his to ease her family out of debt-something that had come about after the death of her father and mother respectively.) bringing with her tales of her day made up of awkward stuttering sentences. She seemed to truly enjoy his company which confused everyone but Mycroft especially.

It was startling the amount of concern flashing in her expression, deep rooted fear for him mingling with anger and betrayal. He did wonder how she could possibly feel betrayed!
"Two years," she did mumble beneath her hand, and then repeated it a few times in a whisper.
Mycroft shared a look with his brother that spoke volumes. Sherlock wanted Isabelle gone, nothing but a troublesome female filling the room with even more troublesome sentiment. Mycroft could not bring himself to send her away, and even if he did she might make a rather large show of leaving with slammed doors and stomping footsteps that were sure to get him in trouble with the other (more uptight) members. Isabelle had a touch for the dramatic, she did not feel anything half way.
"I cannot- I will not let this stand. No, I will have a gesture with Wilder and this injustice will be resolved!" her hands flew to her skirt to hike it up, ready to march towards wherever Wilder may have been.
"May I remind you Miss Long that he works for me, and will do whatever I ask regardless of what you tell him," Mycroft interrupted hastily, the idea of her doing any such thing sending a fright right through to his fingertips.
She halted her progress with a sigh, "Mr. Holmes," she said to the floor.
Mycroft swallowed thickly, "Yes?"

"Why?"

This did give him pause to consider. He didn't really have a concrete answer to give her and so stayed silent. The reason was likely a cruel joke on his brother's part for the sake of having the upper hand, but for obvious reasons no one knew of it. "I like food" seemed ridiculous for the amount of trouble he was going through. "I may be useful to England but I find my life of little worth to me" was just sad, if not true. No, he couldn't say that to her because she'd launch into a speech about how treasured he really was- and would attempt to bring poor Sherlock into it.
Isabelle pressed the palm of her hand against her abdomen, her ribs straining against her corset with the effort of controlling her wild breathing, this of course just made her more strained and unhappy.
"I see. So you are simply greedy then?" she inquired, looking up briefly.
That worked as an explanation he supposed, though it stung like the rear of a wasp.
"Mr. Holmes, that is to say…Mycroft," Isabelle spoke forwardly, garnering a raise of both men's eyebrows, "I do not wish to tell you your business. I have little right to. But I cannot stand by while you kill yourself for sport," she shot a pointed glare at the younger of the two, "We have known each other for merely a month now, but I request… I demand really, that you stop this! Please, if you care for me at all do not let this happen."

Mycroft poked his tongue against the inside of his cheek, taking in the young woman's pleading expression. The light shone against her brown -no- chestnut hair, and at that moment highlighted her thin lips the bottom held between her somewhat crooked teeth. Again he swallowed a lump that had formed uncomfortably in his throat. Had she not said that lark about caring for her, he might have told her no. He should have said no! By God, if he wanted to eat himself to death he had a right! (which thinking on it, was quite a morbid thing for a lady to find out, no wonder she was so tearful). But Isabelle had said "If you care for me at all" and he lost all resistance.

"Very well, I shall ...hold back as it were."

Isabelle squeaked out of pleasure while at the same time Sherlock croaked out a "What?" in utter surprise.
Isabelle clasped her hands in front of her as she walked towards the seated brother. Without hesitation she leant down and placed a kiss upon his fleshy cheek, "I shall keep you to this promise Mr. Holmes. Thank you for your extraordinary caring," she whispered to him before standing straight, "Gentleman," she addressed both of them now, "I…I must apologize for my forward behavior. I shall try to reign in my temper next time we see each other again. As it is, I had best return home before my sisters begin to worry," she cast a wry grin towards Mycroft who understood the unlikeliness of either of her siblings noticing her absence or ever concerning themselves even if they had.
He listened to the ruffle of her skirts as she walked. The soft click of her heels against the hard wooden floor, the nearly noiseless creak of the door as she opened and then closed it behind her, and then she was gone.

"It would seem that the bet is off Brother Mine," Mycroft commented dryly, "Although there are many other things we could put money to."
"That was… odd," Sherlock narrowed his eyes, lips pursed, ignoring his brother's protestations. The younger of the two seemed to glide across the room until he was seated across from Mycroft, "You were lying to her were you not?"
It wasn't the bet Sherlock was upset about, no, as interesting as it was he could have easily let it go. It was that a woman-that Isabelle Long girl- had swayed Mycroft's opinion. He could see it written so plainly on his brother's face, the soft smile that had played at his usually forbidding mouth when he'd assured her.
"No, I'm afraid not Sherlock," Mycroft sighed, "I'm sure I will come to regret the decision but I am a man of my word."
And he would keep his word, for Isabelle. Even when hunger pangs (for one does not come down from an extreme-even if it's only a little bit- easily) needled him painfully like knives, he would instead focus upon Isabelle's neatly seated figure and the interesting conversation she provided for she visited every day without fail.
"But-"
"Sherlock," the elder brother spoke sharply, startling his brother out of his thoughts, "I request that you leave this subject alone and instead focus upon the real reason you are here."

"But don't you see," Sherlock mumbled as he found himself listening to the low rumble of a car engine, "This is the reason I'm here."

"Sherlock, we're here... Baker Street."

The detective opened his eyes blearily at John's exhale of a sentence. Disoriented by his "dream" or whatever you'd like to call it, he sought the familiar. John was still looking upset- angry to be realistic- though he could see just a touch of relief that the two were together again ready to face the unknown criminal.
"You ok?" the Doctor asked, concern lining his face.
Sherlock turned his eyes to Isabelle Long in the car beside him wearing her long grey skirt and T-shirt that had a picture of some anime witch on it. She was scarred heavily from her crash (as he had seen her at the morgue), but smiling. "Thank you Sherlock, you didn't have to do that just for me," she said softly, reaching out to touch his hand. Sherlock could almost feel the soft of her hands, free of calluses much unlike the rest of her.
"Think nothing of it," he waved her off. Literally- for when his hand flew up she retreated back into his Mind Palace where he kept what he deemed the least important information -but still worthy of a place in his mind.
"Sorry, 'thinking nothing of' what?" John questioned, raising an eyebrow at his best friend. Sherlock blinked, "Nothing," he said quickly, "Just…thinking."
His companion seemed to accept this (Sherlock still being high helped) and began his exit from the car. Sherlock followed, letting all thoughts of Isabelle Long leave his mind completely.

Fin.

*Edited ;)

Wrote this just for fun, I had no real purpose behind it except to semi redeem Sherlock and also shove my OC in there. Lol

Please leave a review! I am totally open to constructive criticism!