A/N: I don't know anything about how they cure poisonings so most of this info is from wiki. I'm not a doctor so I don't know how the cure enters the body but I'm pretty sure its injecting.
"Arsenic Poisoning" Sherlock sniffed the water. He quickly searched his mind palace from a cure, "Dimercaprol. Give me the bottle of Dimercaprol" Sherlock shouted.
Roxy flapped her hands "what does it look like" she rushed around the room.
"It's in a blue jar on the self." Sherlock answered not looking away from Valetina. Roxanne found it and brought it to him. "Why do you have this anyway, it's a dangerous chemical."
"You can never be too prepared" Sherlock muttered at he injected the chemical into the assassins body.
Valetina moaned but other than that she was okay. Roxy had called an ambulance and they were now on the way. Soon Swansea was being loaded into the ambulance and driven to hospital, whilst Sherlock was being asked questions of the poisoning by Lestrade.
"That's the second attempt on her life today," he acknowledged, flipping through his notes. "You sure she doesn't need security because she's so stubborn, she refuses any help."
"No, she's fine, I'll just have to test everything she eats and drinks for now, until we can catch the guy who wants her dead." Sherlock muttered as they waited in the waiting room.
Valetina's walked over to the nervous gang, Sherlock stood up. Before the detective could ask, the doctor smiled "She's going to be okay, she's resting now. She wasn't breathing properly so we had to put an oxygen mask on, but over then that she'll completely recover." The doctor patted Sherlock's back, "don't worry she's a fighter, nothing could put her down." She then went to see to her other patients.
Sherlock was about to go into her room, however Roxy stopped him. "She needs her rest; we can talk to her when she's awake."
Sherlock grunted in annoyance but agreed and sat back down next to the best friend.
Lestrade had grown tired of waiting for news on this mysterious 'friend' of Sherlock Holmes so went back to the station to file out papers on the attack. He was to be contacted if there was any change. Mary and John were stuck in traffic and Mycroft. Mycroft was cold and saw no-point in waiting for news on a loved one. He only regretted not being able to catch this murderer, who was trying to end the assassin. So it was only Roxanne and Sherlock who was nervously awaiting an update.
The room was filled with the awkward silence of the best friend and detective. Roxanne had never liked either of the Mr Holmes. They hurt her best friend and banished her from her home and family. They cared little for the emotional damage this coursed the young girl, and wasn't surprised when she betrayed the Holmes brothers by joining with Sherlock's nemesis, Roxy never believed Valetina or more specifically Jade loved Moriaty. She used him as he used her. She used him to get revenge on the men who sent her away. And Moriaty used her to gain info of Sherlock weaknesses. However she left one weakness hidden from Moriaty and most of the world, only a select few knew, such as Roxanne.
"So...your Valetina's best friend?" Sherlock asked awkwardly, he had realised how little he knew of his loved one. He had known her for years but had just realised he knew nothing about her. Not even the simple things like her favourite colour or animal.
"Yeah. By the way did Valery tell you, your friend 'the women' is safe."?
"Yeah, she said she was safe. So by that I'm guessing she has new blackmail material."
"She got herself into the witness protection program. I still have no idea how, and I was with Valetina. You'd sent her to America, her homeland and you asked Vale to protect her. Valetina had to lie about some evidence to weasel her into the program."
"I just want to apologise for what happened, 10 years ago but it was for her own safety, I hated sending her away but it was worth it so that she could live whilst I and Mycroft could find the assassins who were paid to kill the young spy."
"All I'm saying is that you could've told her instead of shutting her out 7 years." Roxanne Hughes and crossed her arms annoyed at the man who argued with himself that he cared and loved the girl in the room resting.
"I know but it was in my opinion a safer plan not to tell her because she would be okay with it resulting in the assassins getting suspicious." Sherlock disagreed and went to get a coffee.
-The detective vs. The Assassin-
Valetina's vision was blurred by the white hospital lights, causing coloured patches to dance around her eyelashes. She moaned in pain and pushed herself up, sensing someone was in the one. She was pushed down roughly by the figure.
"Save your strength dear, don't tire yourself. You're gonna need it."
"Why?" she crooked, her voice barely higher than a whisper. Her voice was coarse and her throat hurt every time she tried to talk.
"I poisoned you silly; I added the poison to you drips. It's ironic isn't it; the thing that's keeping you alive is actually killing you." The man smiled cunningly.
"What-P-poison" she asked quietly.
"I couldn't add actual poison to the drips, it could kill you to quick and I wouldn't be able to tell you my plan and the doctors would notice a decolourisation of the water. No I added tetracycline-a very rare allergy indeed. I believe you're extremely allergic to this type of medication, it swells your throat, making it hard to breath."
Valetina glared at him although she could still not see him, her vision blurred by the decreasing oxygen in her body. She could slowly feel the poison making its affect, absorbing it into her blood stream. Valetina did not talk, she was not going to waste valuable air by talking to the man, and it would only satisfy the murder. But she intrigued her, and the assassin knew she wouldn't have her question answered if she didn't ask.
"Why are you-"she breathed deeply, agony shot through her like a strike from lightening? She couldn't continue but she didn't need to.
"Why am I doing this?" the American looked at the fragile girl in the hospital head who nodded. "I want revenge child, you killed someone I loved so I'm going to kill the people you love. And you have no idea who I am which is all the better. I know you would welcome death, however you would never forgive yourself if your 'friends' I guess we can call them, got hurt."
The life support or oxygen mask she wasn't sure, she hated having pipes attached to her body, was losing the fight to keep Valetina breathing. Her breaths became shallower and shallower.
"You don't have long, and no-one gonna check on you, you'll die in pain and anger like my loved one. Good bye, Valetina, Say hello to Cody for me, you know the body-guard who died for you." He excited by the window, Valetina breathed deeply now, but was restrained by her swollen neck. He knows mostly everything; he must've been on the jet. He's American everything fits.
Valetina was peaceful, she was ready for the light to take her, but before she could drift off into an eternal sleep, her door opened and a dark, tall man walked into the bright room. Sherlock.
"How are you Valery? Glad to see you awake" This was so unlike him, maybe it was because she had nearly died back at the apartment and he felt...guilty. "Sherlock" Valetina choked her vision was going black. "Sherlock... tetrac-" she couldn't finish, her throat had swollen furiously.
It took Sherlock a second to realise what she was talking about. Then he jumped to his feet and screamed "My God you've been given tetracycline, what idiot did this!" unplugged the drips and ran to look for a doctor. In a matter of seconds her doctor was rushing with antibiotics to help her swelling. Sherlock was gestured out of the room and into the waiting room.
An hour later the assassin was in a stable condition sleeping. Lestrade had posted police by the door making sure no-one entered who was unauthorised. The doctor examined her medical sheet and discovered no-one had given her the drug, the only other conclusion was that someone broke into the room and poisoned her. Catching the criminal would be near impossible because Valetina never had a clear sight of the intruder, and the CTV cameras were down. So far he was walking free.
-The detective vs. The Assassin-
A week later Valetina was allowed home. She had most of her strength back after her two poisonings.
"I just hope I won't be back at the hospital so soon" Valetina smiled as the detective got out his eye to open the door. It swung open, the lock had been broken.
"Someone's here-Mrs Hudson is out shopping-who else can it be." Roxanne asked as Sherlock approached her open door and walked into his apartment, followed closely by Valetina and Roxy. The three walked silently up the stairs, the door to the apartment was wide and thrown off its hinges. Five men were waiting for them.
They responded first they attacked Roxy and Sherlock but not the assassin. Sherlock elbowed one spy in the stomach and another in the back of the head. Roxy kicked them in the stomach and stepped on his arm, breaking it.
But even as they fought the way through the spy's, they were losing. They approached the dark haired women and spoke to her in Korean, their guns pointed at her and her friends. She grabbed her own gun and pointed it at the leader, they still moved closer. They don't care, they only want me, they are loyal to their dictator, and they'd die for him.
Valetina shifted her gun and moved quickly. She aimed the gun at her head, her finger flinching on the trigger. They stopped suddenly, realising she was going to destroy herself along with the military plans. "LEAVE!" she commanded, they reluctantly excited the apartment, and they would be back with reinforcements.
"Why did you do that?" Sherlock asked furiously. "You were going to kill yourself so that they would leave. You're so stupid."
Valetina flared up. "They wouldn't have allowed me to kill myself, they want their plans back. Their military plans that I stole and destroyed." She sat down near the fire-place and placed her face in her hands. She breathed deeply and removed her hands, "At least we know they don't want me dead, they just want their secrets back."
Sherlock sat down across from her, didn't say anything and begun to play his violin. He knew Valetina was unreasonable when she was in one of her moods, like she was now. He needed to wait till she was calm to argue why she shouldn't have threatened them with a gun. Sometimes she was so stupid-it surprised him why Mycroft thought she was the cleverer than the Holmes brothers. Maybe because she could feel, and wasn't a sociopath that made her more smart, that was more human?
Eventually the room was filled with Sherlock's calm and beautiful music, to which Valetina, exhausted from everything that had happened in the last few weeks drifted off into a deep sleep.