A/N: It was implied in one of the episodes by Mycroft that there was another sibling, so this is my take on the third sibling.

The dark brown haired girl looked bored as she watched the doctor enter the clinic. "Good news is that there's no breaks on your bones." His face was abnormally sober. She had been coming to this clinic for over five years and never once saw him look so serious even when she had a compound fracture. "Lucy. You have metastatic cancer." He handed her the X-ray.

"I don't understand." Her voice came out strangled in sort of a wheeze. She stared blankly at the X-ray.

He placed her clammy hands in his. "L-Lucy, you have two months left."

A weight seemed to press down on her as she processed his words. Two months. She clawed frantically at her throat, trying to gulp air into her strangled throat. He pulled her into a hug, whispering apologies to her. He had been her primary doctor for the last five years. He should have picked it up. Why didn't he? A tear escaped his eye.

-x-x-x-x-x-x-x-

Sherlock was jumping off the roofs, chasing after the escaping serial murderer. Clearly Lestrade and his very inadept officers didn't understand the meaning of roadblocks. He had warned them of the very high possibility of an escape. Stuck at the end of the roof, the murderer turned around and pulled out a Glock.

Sherlock commented, "It's obvious that you didn't think your escape through. If you had attempted to escape through the alley, you might have had a higher possibility of escaping. But of course, there's me. So no, you wouldn't have anyway."

"Shut up!" He yelled, the gun wavering in the air.

"Also," Sherlock pounced on him.

"Sherlock!" John called out, witnessing Sherlock jump on the man as he finally caught up, his browning trying to get a lock on the man.

They tumbled, Sherlock slapped the man's elbow, trying to loosen his death grip on the gun. As they rolled to a stop, the man still holding the gun pointed it at him. He got up, a large smile on his face blooming.

"Guess what I win-" A shadow swooped down and knocked him over before he could finish his sentence. In a clean move, the shadow pulled him down and sat down on the murderer's unconscious body.

"You're out of practice, Locky," the shadow said and pulled the mask that covered her face. Dark brown hair tumbling down her back, her blue eyes twinkled in amusement.

"Who are you?" John demanded, his browning aiming on her.

She flickered a look at John and back at Sherlock. "Your new partner is an ex-military? Or did Mycroft send you to babysit him." She mock whispered to John loudly, "I'm his ex-babysitter."

"Lucy. You're back. When?" Sherlock asked in a bemused tone, ignoring the stab on him needing a babysitter. His eyes drinking in the sight of her. He hadn't seen her for more than three years. Admittedly he had been busy running around taking Moriarty's web down two years, then there was Moran when he came back.

"Two, three days perhaps. It was fun watching you scamper around."

"Sherlock, you know this girl?"

"John, my sister." Sherlock gestured. "I'd introduce you to her, but I'm sure she knows who you are."

"Your sister? You have a sister!?"

"John Hamish Watson. Army doctor, formerly from Fifth Northumberland Fusiliers. Deployed to Afghanistan, served for three years. Shot in the shoulder. Sent home on what was assumed to be a psychosomatic limp. Rank, Captain." She smirked at John's reaction.

"S-she's just like you two," he finally stuttered.

"Non non. I stole the files from Mycroft."

"Stole from Mycroft!? Tell me she's joking." John said to Sherlock.

"Hardly. You've seen Mycroft?" He huffed. He wondered why she had seen Mycroft first and not him.

"I've seen him. He hasn't seen me. His security needs work." She wrinkled her nose at him and he gave her one of his rare smiles. Typical Lucy. Of course she hadn't seen him first.

Spotting Lestrade finally arriving on the scene, she waved at him. "Lucy!" Lestrade strode over and pulled her in a big hug. "I haven't seen you in ages! You're… really really skinny." He pulled up her wrist.

"Yes. You know how work gets in the way of eating sometimes." She shrugged.

"You know Sherlock's sister!?" John frowned.

Lestrade chuckled. "Haven't you ever wondered why Donovan calls Sherlock freak?"

"Yes… but I thought-"

"Basically Lucy took all her lingerie and hung it all over Donovan's garden."

"She called Locky a fraud!" Lucy sulked. "In any case why are you still doing this anyway?"

"I refused to work for Mycroft."

"Why?"

"I just refused." Sherlock replied evenly. Prior to becoming a detective, he had been working as one of the top ranking MI6. With both of her brothers in secret government business, she insisted on joining and to prevent her from doing so, he quit MI6 and became a private detective with her. He had implied more than once that he missed MI6 but after Mycroft had went behind his back, broken their vows to keep Lucy safe and then sent her out as a spy, he couldn't stand the idea of working under Mycroft. Mycroft had sent her on spy missions! He had been, still was so angry at Mycroft. "We should go back before continuing this conversation." Not waiting for a reply, he climbed off the roof and flagged a cab. "Coming?"

He didn't mean to be that curt. After all these years and he still couldn't be nice. How could he be nice to her? There were many things he wanted to snap at her. How could she not figure why he refused to Mycroft. He wanted to rage at her for persisting in those missions Mycroft gave her. He wanted to rage at her for not letting him come with her. It was a well-worn subject for the last seven years but he wasn't going to give up so easily on it.

Sherlock let the door slam behind him knowing John would open it for her or Mrs Hudson would. He flopped onto his chair, angrily picking up the violin to play on it only to remember that hers to begin with.

"You looked after it well." She smiled fondly at it. "Can I- play it?"

"It's yours anyway," he replied, thrusting the Stradivarius to her. Mentally, he was groaning at himself. Why couldn't he just say something not so curt to her. Something nice.

"What are you doing here?" He pulled his scarf off his neck. His scarf. Technically, it was her scarf that he 'borrowed'. Borrowed implied there was an intention to return. Was borrowed still 'borrowed' after seven years? Lucy was playing the violin. Ever since she left it with him, he never heard her play it again even on the rare occasions when she popped by.

"Tea?" Saint John with his impeccable timing and tea.

She broke from her playing to take the mug of tea from him. "So why are you doing here?" He pressed. She was avoiding the question. Why?

"Bugger off Lock. Do I need a reason to visit you?" Straightening up, she told John, "Going to pass out in my old room. Would you tell his majesty that?"

"Sherlock!" John chided.

He rolled his eyes at John as John went on his tirade on how he should be nicer to his sister.

-x-x-x-x-x-x-x-

Sherlock was surprisingingly in his room asleep when Lucy came out the next morning, John however was in the kitchen making tea.

"Bought some croissants. Not sure if you wanted any breakfast."

"Thanks. You're… pretty nice. I'm surprised."

"Surprised?"

She merely gave an enigmatic roll of her shoulders and offered no explanations. Suddenly a piercing pain streaked through her leg and up towards the rest of her body. Lucy gasped, her hands reaching for her leg. For a moment there, it felt like the pain had numbed all her senses out. It was just her and the blinding pain. She gritted her teeth, forcing herself upright, to pretend that nothing just happened.

"I have- to-" She struggled to pull the words out of her mouth. John might have replied, however she was no longer paying attention. She had to go and get the painkillers from her bag. Where was her bag? Her mind blanked out, her right leg folding beneath her as she tried to walk to her room. Breathe deep, she told herself, pulling herself out of the pain induced trance.

"Room. Black pouch." She told John who hovered worriedly over her.

There was a black pouch lying on top of her small luggage. John swiped it, pulling it open as he hurried back to her. He had been talking to her in an admittedly one-sided conversation when her face turned sheet white and became unresponsive.

Her fingers fumbled, the little bag spilling the contents out. Oxycodone? Methadone? "Why are you taking this?" John picked one of the bottles up, scrutinizing it. She popped a pink one. The pain was killing her. Lucy forced herself to focus on John's lip, forcing her sense to focus on everything but the pain.

"Why are you taking this?" John asked. Her eyes were dilated badly. Pain? Poking around the bag, he found several other pain medication and bisphosphonates. Bisphosphonate? That's for… He put away all the medication, shifting his focus to the girl. "Come on," he carried her in his arms and lay her down on the couch to let her medication kick in.

Sherlock was still sleeping or at least in his room. John thanked for the small mercies. Bisphosphonate? He searched his mind for more information. A kind of medication usually for osteoporosis or fragile bones. Why was she taking them. "Lucy?" She blinked, looking blearily at him. "Lucy. Why are you taking these medication? Are you sick?"

"I'm fine."She waved him away.

"Lucy. If you don't tell me now, I'm confiscating these medicine away."

"No!" She snatched it out of his hands. "You can't tell anyone."

"Oh don't play that with me. I think I already know-" John leaned forward to pull it back.

"What's going on?" Sherlock asked. He had came out to see Lucy and John extremely close together, almost in an embrace.

"Shopping! That's what!" Lucy exclaimed, jerking the pouch out of John's hands and pulling her coat on. "John's taking me shopping!" She tugged him and without waiting for him to wear his coat, she had pulled him out of the house and down the street.

Sherlock stared at the fading view of Lucy. A strange feeling overcoming him. There were the signs but he wanted to be sure. Something was wrong with her and he was going to find out.

-x-x-x-x-x-x-x-

It was a normal afternoon for Mycroft. As normal as it would be any other day, a rumor of terrorist attack, a bomb found in the train, MI5 personnel leaking secrets. So when Anthea placed a file over the one he was reading, he gave her an irritated look that was quickly followed by a look of disbelief when he read the name on it and the tag on it. In fact, he read the name several times and flipped it open to confirm it was really the correct person.

"This is an honorary discharge for Lucinda Holmes." Mycroft stated, his voice was calm despite the frisson of fear running through him. The back of his neck prickled as he flipped to the latest report. Only MI6 agents who died while on missions got a black tag on it.

Name: Lucinda Ashlyn Mary Holmes
Rank: Major
Honorable Discharge
Reason: Died in battle

Died in battle? He had scanned through every mission detail he gave her, never giving her too risky missions. It was the only way to protect her. He flipped to her last record, a medical record.

Metastatic Cancer to the Lungs
Incurable
Estimated time left: 2 months

She wasn't dead - yet. They were taking it as she died in battle. No one wanted their record to be died due to illness. 2 months. The date of the record was time-stamped a month ago. Why had it taken so long for him to get this? "Where's my sister?"

"At the cafe with Mr John Watson."

"And my brother?"

"At Baker street. Your car is ready. I've cancelled your appointments for the rest of the week. Nothing below beta two will disturb you."

Mycroft smiled faintly at Anthea. Of course she'd have known what he'd do. She had always brought Lucy's mission file before it went out and notified him when Lucy came back.

Sherlock was sitting at his usual seat, hands steepled in thought. "Sherlock." Mycroft greeted, sitting before him.

"What are you doing here?" Sherlock asked, annoyed that he had interrupted his thinking. Mycroft threw the file onto the coffee table. The tag said dead but he had just seen her twenty minutes ago. "She's not dead."

"First page." Mycroft flipped it open when Sherlock didn't.

Sherlock stared at the piece of paper, a numbness spreading through him. His heart stuttering beneath his ribcage. That couldn't be right. She couldn't be dying. Lucy the brave, Lucy that had fought Alan Bowen and his gang in secondary school, Lucy who had hung every knickers Donovan owned because she called him a fraud, Lucy who gave her free-spirited ways to stop a terrorist attack and inevitably was drawn into espionage to protect the people she loved the most.

"is there anything we can do for her?" Sherlock asked quietly, his normal condescending tone absent.

"Just to make her comfortable." His knuckles tightened over his umbrella handle.

-x-x-x-x-x-x-x-

That week it felt like they had gone back in time to a time before Mycroft left for university, a time where there was only three of them. Shopping, tea, baking and the endless pointless bickering between her two elder brothers. John dropped by frequently to secretly check up on her and help her administer some of the medication. She had told him about it that day at the cafe and he had reluctantly agreed to keep it a promise. Strangely, whenever John came around to administer some of her medication, neither of her brothers were around. They were always off doing something else or away, leaving her in John's hands.

It was a really good week. Lucy felt alive. It wouldn't last. She knew it wouldn't.

She stumbled, her feet giving way. She splurted into a coughing fit, blood dribbling down her face. Gasping for air, she felt the lean arms of Sherlock envelop her, cradling her head, rubbing her back.

"You'll be okay. You'll be okay," the deep baritone reiterated. Mycroft crouched beside her with the stern look on his face. Lucy saw the fear lurking in his blue eyes. She realized how much she was going to miss them, the smell of Sherlock and Mycroft, the warm tea, the taste of Sherlock's terrible cakes.

"You'll be okay. I promise you." Sherlock held her in his arms as tightly as he bear to hold. He knew he was being selfish. He knew he couldn't promise her that. He had three more weeks right? If God existed out there, if there was a slightest possibility, please let her live. Sherlock had never begged some strange deity that couldn't possibly exist but if there was the slightest chance, even if it meant transferring it to him, he begged desperately for that blind miracle.

"John? John! Where's John!" He searched frantically, tucking her legs over his arms, he hurried down the park where Mycroft's driver was waiting. She was so light, so very light that all he felt was her bones now. Lucy drew stuttering breaths, her bloodied hand was still clutching tightly on Sherlock's immaculate white shirt.

"John!" He burst into the Baker Street. "John!" He carried her, gently laying her down on the prepared bed. Pale and white like the sheets he tucked around her.

Sherlock's lip quivered, watching John and his assistant help make her more comfortable. His eyes were red, he could feel the tightness in his eyes. He wouldn't cry. Sherlock blinked, his hands thrust deep in his pockets, the stain on his white shirt forgotten. Mycroft stood beside him, his shoulders equally tense. Past grievances forgotten, standing there at the edge of the room together for the first time in over twenty years, shoulder to shoulder. "It- It shouldn't be her," Sherlock stuttered.

Jaw working under the weight of all the things he wanted to say, Mycroft nodded. He wanted to scream and weep for taking his sister away. She should be gone in a fiery blaze, in action, in her prime not on a white bed on white sheets that made her white face looks so white. He swallowed thickly, reaching for his phone.

"Anthea. Get me blue bedsheets." Mycroft said hollowly to Sherlock. "She always liked blue bedsheets."

There were many cruel things in the world, both natural and human induced. To Sherlock it was the silence in her last three weeks. He always valued silence and found it a requirement to access his mind palace, now in the excess of the silence that seemed to ring, he found the only thing he wanted was the noise. The sound of her laughter, the bickering and teasing, the way she scolded him for using the mugs to dissolve human parts. Noises he would never hear again.

You never know what you had to lose until you had lost it.

She was so skinny, so dosed on pain killers that she was barely awake anymore. Mycroft sat there, his hands were clasped on his knee, watching her. Waiting. Waiting for the flutter of her eyelashes that indicated she was awake. Sherlock said it was the silence that was the most painful but it was the sound of her breathing. The feeling of hopelessness that he was the most probably the most powerful man in Britain but there was nothing he could do to protect her.

"Hello Crofty," the girl said as Mycroft entered his study. She was lounging on his sofa, with her grungy boots on the sofa facing hers.

He sighed loudly. "Must you always do this?"

She quirked a lazy eyebrow at him. "Do what?" She asked innocently, her expression said otherwise.

"Put your dirty shoes on my sofa. You know how much I dislike that." He sunk down into the sofa facing hers and she moved her feet, this time onto the sofa's rim. A streak of mud trailed down the velveteen sofa. She chuckled at his look of horror which only caused Mycroft sighed louder. "What do you want Lucinda."

She frowned and her lips pressed into a thin line. "You know I hate that name as much as you hate Michael Crofton." She smirked at his eyebrows furrowing deeper. Deciding to not to be such a pain, she threw a thick manila folder onto the coffee table and inspected her neatly trimmed nails. "Stop giving me pain in the butt cases. Mummy would think you're trying to kill me." She rubbed her dirty foot on the sofa. "Might as well you know. Since you'll get Thomas to clean it. It's still Thomas on sofa duty right?" She grinned.

All those times, the memories of her purposely aggravating him, her smart alec mouth constantly getting her into trouble.

"William Sherlock Scott Holmes! Michael Crofton Alexander Holmes! What do you think you two are doing?" She glared angrily at them.

They groaned. She hadn't called them that in years not since they buried the awful names and picked up their own self-made derived names. "Well whatever it is you're going to, I'm coming."

"It's a secret government meeting. You're not supposed to come." Mycroft explained.

"Yea? Like that ever stopped me." She tossed an ashtray to him. A Buckingham palace ashtray. "Security there's pathetic by the way." Mycroft felt a migraine growing.

Would things be different if he had done it different? Mycroft gripped his head with his hands. He didn't care if his usually perfectly styled hair was messy or if his suit was rumpled. He hadn't had a proper sleep for over the last three days or taken a shower for the last two. If it hadn't been for a combined effort from John and Anthea, neither of them would have eaten something for the last few days either.

"Mycroft?" she whispered. Her fingers twitched. Her eyes roved the room. She took a shuddering breath.

He enveloped her small cold clenched fist with his. "I'm here." He placed her hand on his face.

She coughed, struggling for breath. "Be nice to each other okay?"

Behind him, Sherlock shuffled closer. He placed an awkward hand on Mycroft's shoulder, his voice ever sarcastic though it was missing the edge. "Well you'll have to be here to stop us bickering, don't you?"

She smiled wanly, so slight the smile was that Sherlock had only seen it because of the two small upturned corners of her mouth. He propped her to rest between Mycroft and him as they laid side by side on her bed.

She took another loud, painful breath, her chest falling then stilled.

Sherlock ran his hands through her hair, pressing a kiss on a temple. Mycroft kissed her cheek, an act he had not done since childhood.

"The things you do for yourself are gone when you are gone, but the things you do for others remain as your legacy."

― Kalu Ndukwe Kalu

Sherlock stood there watching the dark hole swallow Lucy up. He was numb apart from that dull ache in his chest. An ache that he couldn't get rid off. The blue scarf. He had borrowed it in retaliation of her dumping his experiment into the sink.. It was her favourite scarf, an expensive one. The first one she bought with her first paycheck. He had assumed that she would fight to get it back but she didn't, she never had the time to. The bomb plans she stole back with her adept shadow skills, she left it with him for safekeeping. Just like the violin, just like the skull. Who was he going to keep it safe for when there's no one to return it to now?

"It's all your fault. If you hadn't sent her to steal the bomb plans back, she'd still be beside us, me. Safe. She wouldn't have spent all those years alone." Sherlock pressed his hand against his wet eyes. "I'd have had more time with her." He hadn't really meant it. He was just so numb then angry at himself that he felt it was going to crush him.

"They shouldn't be burying her." Mycroft said. He had picked the blue dress that she loved, wearing the long black duster coat that she wore for seven years, the coat that he had bought for her. He had told her it was a set of three and got one similar for each of them. "She would have wanted to go with guns blazing. Like a dancing fire. Ashes, flying free."

John approached them. "Lucy always knew you two would have figured it out sooner or later. She felt it was easier to pretend everything was normal." He handed them a disc. "She wanted you two to have it."

It was a video. Something she had done when she was first diagnosed in Paris. She was looking almost healthy.

"Hi you two!" She waved, breaking into one of her infectious smiles. "I suppose by now, I'd be dead. Either Sherlock or Mycroft found this disc or perhaps I asked someone to pass it to you. Still. I'd be dead. That's fine. I just wanted to confess something. It's insanely important. Sherlock." She pointed at the camera. "Billy the skull is not real. I made it and you never realized it! So I win!" A tear rolled down her face. "God, I wish I could see your face when you heard that."

She wiped the tears away and composed herself. "Mycroft. Your security system. I planted a virus in it and it's been running for years. No one realized it. It's okay. It's a benign virus. It only activates when an outside, unidentified source tries to break in. So I guess it's a bit like a white blood cell now. So I guess I win too! It was a running joke to be honest. I wondered how long it'd take you to detect it." Pausing, she looked down at her hands. "It's okay Holmes brothers. You still have each other. Promise me you'll do all the things I couldn't finish. Ride a bike, skydive without an emergency chute. Learn every language on earth, drink tea with each other and eat Sherlock's terrible cakes. So this is goodbye now. I love you two." The video went dead.

They looked at each other. "Tea?" Mycroft asked.

"Only if you'll eat my terrible cake." Sherlock replied.

They chuckled hollowly. A tear slipped down each other's face.