A/N: So! Here it is! The chapter that most of you have been bugging me for! I've had the backstory written for a while. You'll know why Castle is so desperate to hide his past after this chapter. Let me know! :)

With a quivering heart, he stands at the far corner of the bookshelf that separates his office from the living room, reaching for the top shelf with a weak arm and grabs the book. He tugs it from between the wall and the book next to it and brings it down in front of him, holding it in his hands like a delicate flower as he paces towards his desk. It's not until he's leaning back against his desk for support that he has the nerve to crack open the hard cover of Voltaire, seeing a picture he hasn't seen in almost twenty years.

He feels his heart stop when he sees the photo. Add some age, that's the face he saw this afternoon. But...

It just can't be him. It's not possible.

He feels his eyes burn as he takes the photo from the book and lets the book fall from his hand with a clattering thud onto his desk. He feels his heart shatter with guilt when he remembers the last time he saw his face. "I'm sorry, Tommy."

The sound of a knock on the door sends him jumping off the edge of his desk, snapping himself out of his guilt-ridden mind. He takes in a long, deep breath as he tears his eyes away from the photo and puts it back in between the front cover and the first page, wiping his face roughly to rid himself of the physical evidence of his emotions. He moves through the silent darkness of the loft, his fear biting at the back of his mind, wondering who would be knocking this late. But once he opens the door, he feels his blood grow thick, his heart stop, and his breath hitch in his throat.

"Kate..." He says in a weak voice, noticing right away her lowered brow and focused eyes, her lips turned down into a frown as she looks over at him. When she doesn't respond, he feels himself lose her. She knows, he thinks to himself as he lowers his gaze down to the floor, watching out of the corner of his eye to see her slowly pace her way passed him and into the loft without a word.

He slowly slides the door shut and takes a pause, hardening himself against her judgment as much as he can before turning to her with a stern look.

He's never told it to anyone. Not even his own mother.

But now... she's going to be the first to find out.

"Your file..." She says in a voice just above a whisper. "I checked it again..." She says, still looking at him as if she doesn't know who she's looking at, speaking to him as if she's lost. "It didn't say anything about this."

"That's because when I joined under the name 'Richard Castle'... it wasn't my legal name yet." He says with what he knows are brimming eyes.

He looks towards his office and unplants his feet from the floor, moving towards it and rolling his shoulders back, as if to take this all in stride. Once he's at his desk, he flips open the cover of the book and takes the photo with his thumb and forefinger. He takes one last look before turning to find her a few paces into the doorway, still looking at him with a lowered brow. "This is the only proof I have that what I'm about to tell you isn't just another crazy story."

He hands her the photo and still glaring at him, takes it and holds it in front of her. Once she looks down to it, he feels his heart constrict.

She can't feel anything, her emotions are long gone from her, even now as she looks down at this grainy photo he handed her. It's faded, but his features are clearly defined. His hair is shorter and a bit spikier. He's sitting down on the ground in front of a large transport truck, wearing a black t-shirt, cargo pants, and a bullet proof vest with an assault rifle lying in his lap. And next to him is a man around the same age with his arm around Castle's shoulders, his hair is blonde, short, and spiked, his smirk cocky and Cheshire, wearing the same attire as Castle with the same rifle in his lap.

"The man in that photo... his name was Thomas Wayde." His voice starts, shaking as it comes out. "But we called him Tommy."

Her eyes look up to him and she can clearly see them brimming.

He draws in a long breath, "I was a nineteen-year-old high school student on graduation day. I had no ambitions... no plans and no real goals. At that time, being a writer was just... a fever dream. Tommy was there, he'd graduated a few years earlier... and he offered me a job. He said it would mean a few months of intensive training and two years out of the country. And since I had no real family I'd be leaving behind and the money was too good to pass up at that age... I took it."

She lets the photo fall to her side as she silently stands a good distance away from him.

"What it was... was a few wealthy investors wanted to mine precious minerals from a part of Central America. And to save on the money, they decided to give the locals jobs running their operations. But the people down there were being terrorized by a group of people who were dangerous. They'd hold entire villages hostage until they got what they wanted and they didn't care who or what they killed as long as they could make a dollar off it. So... our job was to make sure they were safe."

His heart starts to break from the guilt as he looks away from her, feeling a hot tear leak from his eye.

"But our duties doubled... as making sure the workers stayed in line." He says in a shaky voice. "We were slave drivers, Kate. I hated every minute of it, but... luckily, my mother's acting skills actually paid off and I knew how to pull a punch when I needed to. It didn't happen very often, but when it did... it... was incredibly hard... having to stand by and watch it happen. After a while, the workers seemed to understand and started to just do their jobs and collect their pay."

She still can't feel anything. Her mind is numb... she can't think of anything... can't feel anything.

"Tommy had taken me under his wing, so to speak. He'd... taught me everything he knew. The gang that was terrorizing the locals would have a few skirmishes with us here and there, but after about a year, they seemed to give up and move on. Things seemed to settle down after that and I thought it was smooth sailing until my contract ended. Me and Tommy would pass the time doing... target practice, hand to hand training, survival skills. He was one of the best friends I ever had, Kate."

But when he feels his mind think of what he's about to tell her, he feels his eyes burn again.

"I was nearing the end of my time..." He says with an intense shake in his voice, "when we were escorting a load of cargo from the job site to the coast to be shipped out. It was pretty late in the night and it was just another routine escort. So, most of the other guys seemed pretty relaxed. Tommy was at the truck in front of me... and I blinked." He feels another hot tear leak out onto his cheek, feeling weak and pathetic. "Next thing I know, I'm on the ground and the truck in front of me is upside down in flames and there's muzzle flash coming from both sides of the jungle."

She finally feels her heart beat and her brow arch in concern.

"I crawl to cover and once I'm safe... I see Tommy... lying on the ground underneath the truck, trying to pull his leg out. I could hear him calling for help over the gunfire. And looking back on it, it's easy to tell myself that I was one second away from running after him, but... at the time... most of us had never seen action like that during our time... and we were scared. We had a different set of rules from the real military, so no man left behind wasn't really our official policy. So... when I heard the order to cut our losses and run back to the escort vehicles to get out... I took it."

He feels so small, so guilt-ridden, and so weak, knowing full well that she can see him in silent tears.

"I left Tommy trapped under a pile of flaming metal because I was scared and wanted to save my own life. And... I found myself back here in New York a few days later and I started writing. Once I got the paycheck... I used the money to get In a Hail of Bullets published... and when it became a best seller... I thought I never had to think about that time in my life again. But by the time I'd met Kyra, the guilt had started to get to me and her family noticed. So, when she left me and I met Meredith, Meredith made me feel... a lot better about myself when she fawned all over me the way she did. And when she gave me Alexis... I never thought about what I did again and swore that I would never mention it to anyone."

Kate looks down at the photo again, then back up to him, the light from the street lamps out on the streets shining an orange light onto the tracks of his tears. "Martha? She doesn't know?"

"She thinks I spent two years traveling abroad like she told me to."

"And... and Esposito and Ryan?"

"I only told Espo because it was the only way to get him to keep his damn mouth shut after he called me out for making that shot when you were kidnapped a few days ago." He says, annoyance making his jaw tense and teeth grind as he shakes his head. "I only told Esposito what I was. But... you're the only person that knows about Tommy. I thought that..." He says, emotions clogging his throat again, "I thought that I'd put it behind me after all these years, but... ever since Esposito found out, he's been on my case about it non-stop. Proud soldiers like him have a real pet-peeve with private mercenaries which is why he's been so indifferent towards me lately. But... I guess it was bound to come out eventually. Even Deep Throat told people what he did right before he died."

She shakes her head, her heart tugging as he admits that it's haunted him so badly, and he's never told it to anyone except her.

"I was perfectly content playing the naive writer slash careless millionaire playboy. But... when I met you, I found myself being put into situations that forced me to choose between keeping you safe and keeping my secret. And Kate..." She feels her heart tug again when he says her first name with a tremble in his voice, "if I didn't care about you so much, the decision might be a little harder. But the truth is... I'd choose keeping you safe in a heartbeat."

She takes one last step toward him, her eyes down on his lips as she comes to stand in front of him, just inches away.

"But Kate, if this changes the way you..." His words stop when she lifts a shaky hand, putting her fingers over his lips as her eyes narrow and looks down to her fingers.

After a moment, her eyes flick up to look at him and her hand moves from his lips to frame his face. Her other hand drops the photo to the ground and takes his forearm, moving his hand around her waist as she leans forward, pressing her front up against his, then moving the hand she used to tell him to hold her up his arm until it's around his shoulder, still searching his eyes deeply.

"I want this too much to let that change how I see you."

"But, Kate, in the morning, you'll-"

"I'll decide how I feel about it then, Castle." She says, her arms slowly weaving themselves around his neck. "Because right now, I wanna be with you before I lose you to this." Her heart wants to feel close to him again, she wants to pull the man she fell in love with back to her, whatever it takes. "I wanna feel close to you, Rick."

He lets out a hard breath, his shoulders breaking free of the weight they feel burdened with, but still quivering under her hands. He lets his eyes drift shut and leans down, resting his forehead down against hers, finding a deep solace in her presence, in her want to be with him despite his past.

She lifts her head off his, leaning back and looking into his eyes again. Their eyes lock as she takes a step backward and folds her hands into his, walking him through the open door to his bedroom.