The ending of "Spiral" got me thinking. This will be slightly off the canon, but hopefully not too much and the story will make it worth your time. I went in and rewrote this as really a first chapter to what hopefully will be a multi-chapter story. Also, I found some medical stuff that did not make much sense so I tweaked that too.

Images and flashes of of memories replayed themselves in Callen's mind. They were brief, abbreviated snippets that alone did not seem to make sense, but together, they seemed to tell a story.

Callen remembered the vial being thrown on the floor and the isolation door closing leaving him inside. He remembered coughing and the blood on his hands. He remembered looking up and seeing people in isolation suits hovering over him. Then there is nothing for what seems like a long time. The next memory fragment was his partner Sam's face and then Hetty's. He heard voices, "We're losing him. I need more blood." Another face appeared in Callen's memory. It was his mother. She was leaning over him, looking at this face. But that was impossible, wasn't it? His mother had been dead for over thirty years. The most overwhelming memory was the insistent beeping that did not seem to go away. In fact the beeping was getting louder and louder. It finally occurred to Callen that the beeping was his heart monitor and the reason that it was so loud was because he was actually awake.

Callen let a groan escape his lips. He felt terrible. Every inch of his body hurt and he was so weak, it took all his focus to just open his eyes. But he forced his eyes to open and saw the familiar and comforting outline of his partner, Sam Hanna sitting in a chair by his bed. For a moment, he thought he saw somebody else, but the outline was outside his line of sight and he did not have the energy to move enough to confirm what he thought he saw.

"Well. Welcome back to the land of the living," Sam said. He tried to sound flippant, but the relief that his partner was actually alive and awake was evident in his voice.

"Where am I," Callen asked, vaguely annoyed that he cannot speak above a whisper.

"You are the Norris Cancer Center at USC," Sam said. You were transferred here about four weeks ago from the CDC Headquarters. "You've been out the whole time. It was pretty much touch and go for a while."

"What the hell happened?"

"You almost died. That's what happened," Sam huffed, trying to sound tough and not entirely succeeding. "Spiral almost killed you. Luckily they had the antidote to treat you and…," Sam paused uncomfortably.

"And what?"

"And apparently you are in the one percent of the population that could have a negative reaction to the antidote."

"Lucky me ," Callen said ruefully.

"Yes. You were lucky. The antidote destroyed your ability to produce bone marrow. You know what that means?" Callen knew vaguely and Sam continued. "It means that you would die. Your immune system would fail and you would need constant blood transfusions just so your body would function. It means that you needed a bone marrow transplant. And you were lucky that Hetty found a donor."

"Bone Marrow? A Transplant? From who?". Callen was no doctor, but he knew that finding a genetic match close enough to do a bone marrow transplant outside of a family was almost impossible.

"Well there's a whole story there," said Sam.

"Sam," Callen's voice was weak, but the implied warning was loud and clear. Callen hated surprises and mysteries. They usually did not go well for him. "Where did the bone marrow come from?" Callen demanded again. As Sam vacilated on what to tell his partner, Callen heard a new voice.

"Me. The bone marrow came from me." Callen gaped. The woman that stepped into his line os sigh, looked just like his mother. Petite with long curly brown hair and large brown eyes. Callen could tell that she was used to laughing more than frowning although now she wore a concerned and even slightly frightened expression. Callen realized that he did remember what his mother looked like that last time he saw her - she looked just like this apparition in front of him.

"Dobroyo utro, Grisha, (Good morning, Greg)" the young woman said in perfect Russian. "Meny zavout Lili, no te meny znall kak Sofia (My name is Lily, but you knew me as Sophia.")

"Ya tvoya sestra (I am your sister). Callen stared as Lily Tomoshenko, CIA Agent currently on loan to NCIS in Washington DC, decimated everything he ever knew or thought he knew about his life.

This is my first cross over story and my first attemtp at NCIS-LA. I have always really found Callen to be such a sad, lonely character (I get it that's the point), that he just needs somebody. Then Lily came to be (would love it if you read the other stories) and then one day it dawned on me that given her own history and the unknowns in her life, she could be a perfect long-lost sister for Callen. It will call for some minor changes to canon, but I think I have them figured out. By the way - the Russian is authentic. Its the best that I can do phonetically, but it is my first language although I have been speaking English for most of my life now. Please read and review and provide any thoughts and comments. Please let me know if this is of interest to you. Thank you