A/N: This is loosely based on a Twitter RP with TheArmyDoctor and DeathfrisbeeSH. I have compiled this from memory and Alannah is my invention.

All recognisable characters have their own Copyright to Sir ACD and BBC; I'm just borrowing them.

Chapter One

The woman stood nervously outside 221b Baker Street. She was dressed in a cream Gucci dress and gold Jimmy Choos. Her dark hair was baby soft and cut into a modern pixie style. Taking a deep breath, she rang the doorbell, unsure whether she hoped the occupants would be at home or not.

A kind-faced elderly lady opened the door. 'Yes dear, can I help you?' she smiled

'I'm looking for Sherlock Holmes. I was told he lived here.'

'Go on up, he's on the first floor, the door will be open'

'Thank you' the woman smiled and made her way up to the first floor flat, knocking as she pushed open the door. 'Sherlock?'

The man in question turned from his position by the window and froze. His voice cold he spoke to her; 'What are you doing here?'

'Is that any way to greet your sister?'

Sherlock barked a bitter laugh. 'Sister? We may have shared a womb once, Alannah, but you stopped being my sister a long time ago.'

'Yes, seven years ago. I remember very well how you, Mycroft and mummy publicly disowned me. A lot has happened since then. I have changed and I miss my baby twin'

Sherlock frowned. 'What is it you want? You would never come to me unless there was something you wanted. A deal gone bad? Got the Russian Mafia after you?' He took the time to look his sister over. She was thin, both of them had always had a slender form, but she was very thin. Her hair was soft, much softer than he would expect of a 35 year old woman. Her expression was pinched with pain, though she was working hard to hide it. 'You're ill. Are you using again?'

Alannah looked hurt. 'I've been clean for over ten years. More than can be said for you, brother.'

'Then why are you here. You obviously want my help, so spit it out.'

She swallowed. 'You can't help.'

Sherlock snorted. 'You wouldn't be here if you didn't think I could help. Selfish to the last – you will never change.'

Alannah felt a tear slip down her face; she had never been as good as her brothers at hiding her feelings. 'Maybe it is selfish to want to make peace with my twin brother. Look at me – really look. What do you see?'

He looked at her again, the deduction slipping into place. 'You're ill. Cancer – your hair is new growth after chemotherapy. You obviously finished treatment a while ago, so why come to me now?' He gasped, 'Oh. Oh … I see. How long?'

Alannah closed her eyes, unable to look him in the eye. 'Maybe 6 months. Cerebral brain tumour, inoperable. 3 months aggressive chemo and radiotherapy didn't touch it.' The sound of retching made her open her eyes. Sherlock was bent over the kitchen sink losing the contents of his stomach, she sighed. 'I'm sorry.'

He takes his time rinsing his mouth before turning back to face her. 'Why are you sorry? Traditionally, that should be my line.'

'I've just hit you with information that I've had months to process and accept.

Sherlock smiled suddenly, 'John'

'John?'

'My flatmate. Ex-army doctor. I'm sure he will be able to help.'

Alannah sighed; she should have expected this. Sherlock would see her illness as a problem that he needed to solve. 'I have been poked, prodded and scanned enough to know that the doctors are telling the truth when they say there is nothing to be done.'

'More chemotherapy'

'Would give me a year at best, but at what price? I've ..' Alannah stopped, unmoving and unblinking. The seizure lasted just a few seconds before she continued, unaware that she had paused, 'accepted it.'

Sherlock said nothing about the brief absence seizure, but looked at his sister, almost pleading. 'I trust John's medical opinion implicitly. If he concurs, then I will accept it too.'

Alannah nodded her agreement; she knew that John would have no choice but to confirm the diagnosis and prognosis. Pulling out a card, she handed it to Sherlock, working hard to keep him from seeing how ill she was currently feeling. 'This is my address and number. Call me when John can see me.'

'You're leaving?'

'You want me to stay?'

'Of course I want you to stay' [I don't know how long we have left together] 'tell me about you. You say you have changed. How?'

Alannah sat on the edge of the couch. 'It's mostly since I've been properly ill, so over a year.'

'You have been ill for a year?'

'Closer to eighteen months. Things had to change when I started chemo; it made me really ill. I could barely keep anything down for 2 days after each session. The sessions were weekly.' She stops, visibly upset, looking drawn.' Sorry. I know you don't like emotional displays.'

Sherlock surprised her by sitting next to her and pulling her into an awkward hug. 'Do Mummy and Mycroft know?'

Alannah stiffened in his embrace. 'Please don't tell them.'

He pulled back to look her in the eye. ''Lannah, they have a right to know.'

She shook her head, 'Please, promise me you won't tell them, Lock, promise me.'

Searching her face and seeing her genuine distress, he acquiesced. 'I promise; on one condition. Live here. You know what's coming; that you won't be able to live alone. Let John and me take care of you.'

Alannah looked at her brother confused. 'You don't do caring. Why is this different?'

'Let's just say that I have changed too in the past few years.'

'Since your 'suicide', you mean?'

Sherlock grimaced, as he always did whenever the subject of his faked suicide was brought up. 'Partly, but mostly because of John's influence.'

'Are you and he … together?'

Sherlock nodded. 'It happened a few months after I returned. Moriarty forced me to acknowledge how I felt.'

Alannah smiled. 'I'm glad. You know I couldn't believe it when I read in the papers about your suicide. I tried to contact Mummy and Mycroft, but they wouldn't take my calls. Then you came back and your name was cleared. I nearly got in touch then, but I was afraid you would reject me too. Then I found out I was ill …' She yawned.

Sherlock smiled. 'You're practically asleep. Why don't you have a nap? Use my bed, John won't mind.'

Alannah nodded, genuinely too tired to argue. Once he was sure she was asleep, Sherlock made arrangements to have Alannah's things brought to Baker Street, then he sent a text to Lestrade informing him that he was currently unavailable for cases. Finally, he called John and briefed him on the situation. John promised to return home as soon as he could and that he would request a copy of Alannah's medical records.