A/N: I don't own any of the "Criminal Minds" characters and I am not making any money from writing this.

Please forgive any minor spelling or grammar mistakes, English is not my native language.

I hate myself for writing this. I really liked Nathan Harris, and Spencer has suffered enough, but this idea popped up in my head and wouldn't leave me alone. So here it is. If you don't like angst/tragedy, you better not read this. I've been thinking about how Spencer would cope, would that make for a good fanfic, and I also want to tell Casey's story. But for now, this is just a oneshot. I imagine this takes place sometime in season nine or ten, probably.

Nathan was sitting at the desk in a very corner of the library, sighing as he turned the page. He only managed to read half the page before feeling an urge to write something down in his notepad again. "Inside the Mind of a Sexual Sadist". One of the many books he had read; one of the many on that subject too. He still had some trouble understanding it all, but rationalizing those things, knowing that many experts studied them and tried to understand them, would always make him feel better, give him some much needed hope. The librarian would usually allow him to check out almost any book, including the ones about psychiatry and psychology, but he enjoyed just being in a library, reading. A welcome change of venue, if one could call it that.

Nathan sighed, looking up from the book for a moment. He glanced at the clock on the wall. Twelve am. He had a therapy at 12:30 am. Then lunch at 1:30 pm. Then it was time for medication... Nathan shook his head and continued reading. For some reason, Nathan would always chose the desk in the very corner of the library (if it was available), near large bookcases; isolated, as private as possible. Like he was ashamed of something... or he just wanted to feel normal again. Of course, the librarian (who was actually one of the guards; most of the staff had some sort of security training) could still get a good look at him, if he tried. Those were the rules, and rules had to be followed.

Nathan's mother would still come to visit him, pretty much every week, and she'd call him almost every day. Though it clearly hurt her seeing him confined there, she obviously knew that was for the best, and was overjoyed whenever Nathan would make progress, or simply appear happy and content with himself, despite the circumstances.

Nathan still kept in touch with Spencer Reid too, but mostly through letters and an occasional phone call. Spencer was a busy man, after all; plus, Nathan sensed that Spencer was afraid of stirring up bad memories. Still, he clearly didn't forget Nathan, and he didn't give up hope on him either. Spencer always seemed so understanding amd supportive; Nathan felt like they had a lot in common, though he never dared to bring that up, for some reason. That kept pushing Nathan forward, giving him hope. He liked that; and he needed that.

Things were actually working out pretty well. He was no longer having those thoughts, those urges... not nearly as often as before, anyway. Just once every week or so (wet dreams not included). Apparently, long-term therapy in a controlled environment, combined with the use of antipsychotics, can go a long way. That's what he constantly reminded himself of; as well as his mother, and dr Reid.

Nathan shivered, wondering what would have happened had he never approached Spencer Reid on that subway station. Or had Spencer not arrived in time to stop the bleeding and call the ambulance...

Almost eight years. Eight years of being institutionalized. He was scheduled to be reevaluated in three months. Only three more months-a little over ninety days...

Nathan snapped out of his thoughts as he heard the unmistakable sound of the library door opening. A young woman walked in-quite young, maybe even a teenager. He quickly realized that she was a patient there; she was wearing that white plastic bracelet on her right wrist, and she looked too young to be a doctor, nurse, or a guard working in the hospital; not to mention a lack of uniform. Their eyes almost met; Nathan looked away instinctively, focusing on reading again.

Just when he turned another page, he heard another familiar sound; footsteps, approaching him. He didn't look up, trying to focus on a chapter about. But when the fellow patient sat at that same desk, on a nearby chair, right next to him, he couldn't really ignore her anymore. And he didn't want to offend her, make her angry; who knew what she was in for?

She was the one to speak up first. She seemed calm and non-threatening, but there was something deep in her eyes that made Nathan shiver... something that he recognized. "Hi."

"Hi," Nathan replied, trying to conceal tremors in his voice.

The girl remained quiet for some time, her eyes roaming over him... almost like she was trying to study him, somehow. Nathan was just looking back at her, trying to remain calm. "I'm Casey," she finally introduced herself, holding out her hand. "Casey Burke."

Nathan shook her hand, feeling a bit more comfortable. "I'm Nathan. Nathan Harris." He swallowed a lump in his throat, shifting in his seat. "So... are you new here? I mean, I haven't seen you around..."

"Yeah," Casey confirmed, nodding her head. "They put me in here little over a month ago." She frowned. "So, you've been here for a while now, huh? No offense."

"Yes. For, uhm, few years now."

Casey nodded her head, then looked around. "So... are you doing well?"

"Yes. Pretty good... now. It took some time, but I'm doing well."

Casey sighed, turning towards him again. "Nice... I'm glad to hear that." She chuckled bitterly, running a hand through her hair.

Nathan eyed her, choosing his words carefully. "Don't give up hope", he said softly. "You're young. You just got here. There's plenty of experts in this place."

Casey sighed, clasping her hands. "I hope you're right." She smiled slightly. "Thank you." Her gaze landed on an opened book on the desk, in front of Nathan. "You like reading?" she commented more than asked.

"Yeah... it helps me relax... understand myself better."

"Same," Casey said, leaning back in her chair. "That's why I'm here. I just wanted to talk to someone first."

"Seriously... how did you accomplish it?" she suddenly asked him, and her voice sounded a bit more... determined. Sharp.

Nathan shivered. He felt that something was odd, but didn't want to call for help just yet; maybe Casey was just frustrated and he could give her some useful advice. He couldn't helo but wonder how would Spencer Reid handle that. Before he could answer, Casey elaborated. "You say you're doing better now. Much better. How?"

Nathan gulped. Eventually, he simply decided to be honest and list all the things that had proven useful. "Therapy. Medication. Effort. Remorse."

Casey scoffed, glaring at him. "So, all the usual bs, huh?"

Nathan frowned, feeling cold sweat run down the back of his neck. "Casey, you've only been in here for a month."

"I wasn't referring to that," Casey replied, then chuckled bitterly. "Seriously, that's all you have to tell me? That's the best advice you've got?"

"You have to try," Nathan continued, trying to sound as comforting and convincing as possible. "To believe in yourself. And be willing to change. The people in here are the experts, and they want to help you. That is a great start, believe me."

A short, tense silence ensued. Nathan glanced at the librarian. He was not focused on them at the moment, working on the computer. He could see them from his position, but he probably couldn't hear them, at least not clearly. Casey scoffed, leaning over to Nathan, causing him to flinch.

"You never actually murdered anyone, right?" she stated more than asked, somehow sounding both disappointed and amused at the same time. "No blood on your hands?"

"No", Nathan replied, feeling his stomach sink, color leaving his face. Words came out before he could stop them or even fully consider them. "And you?"

Casey smirked. "Seven", she replied, reaching under her gown. Nathan barely had the time to process that admission when she pulled out a shiv. "Going up eight", she said, gripping the blade tightly.

Before Nathan could really react, Casey stabbed him in the gut. Sharp blade ripped through his flesh with agonizing force. Nathan screamed, feeling pain ripping through his muscles, his body writhing in pain as blood gushed out of the stab wound just above his navel. He cried as Casey pulled the knife out, allowing a stream of blood, mixed with pieces of ripped flesh, to spill over the floor.

Nathan was terrified, confused, and in an agonizing pain. He felt all the strength and energy rapidly drain away, his body growing weak, his eyesight turning blurry. He tried to call for help, but his body was so strained and weak that he could barely breathe. In the very next moment, Casey raised her hand and attacked again. This time, she stabbed Nathan in the neck; the blade sliced right through his aorta.

Nathan could only make out a weak, silent groan of pain before he collapsed on the floor, pain and weakness taking over completely, his whole body turning limp and cold. Through the blurr that clouded his big brown eyes, he saw Casey being tackled on the floor, by two security guards-the "librarian" and someone else. Her voice echoed through the library; an eerie mixture of anger and mockery.

"Call SSA Spencer Reid! Can't wait to meet him again-now..."

Those were the last words that Nathan Harris heard. Though his mind was fractured from the sudden surge of pain and fear, he was able to process them; as his thoughts began to dissipate, he saw Spencer's face, and remembered his wise, comforting words.

"You sought me out to try to understand how not to hurt people. It's a far more important part of who you are than the one that scares you."

And then, an oblivion.