Charlie's hands didn't shake anymore.
His breathing and heartrate held steady, in control. Not like the first time he'd pointed a gun at a man and pulled the trigger. Then his hands shook so much, he was lucky he hadn't miss.
The memory came back to him every time he held a gun. In his mind, he could see the suspects threatening Don's life. They forced a gun into Charlie's hand. They told him to shoot a third hostage, or they would kill Don. Charlie knew what Don wanted him to do. Don was the FBI agent, willing to sacrifice his life for a stranger. Don didn't know how far Charlie would go for his brother. Before that day, Charlie hadn't realized the things he would do to protect Don. That day he learned two things.
He would kill to protect his brother.
And he would enjoy it.
Charlie understood the concept of killing. His mind understood the textbook concepts of shooting a gun, the vital areas of the body he needed to hit to ensure death, even how to calculate the trajectory and speed of the bullet. Charlie never expected the emotional response from killing.
Before that day, Charlie had abhorred violence. He could count on one hand the number of times he'd fired a gun. The thought of taking another human's life made him sick. Amazing what changing a few variables in the equation could do to the outcome.
He had squeezed the trigger, marveling at the reaction. The blood, bone, and brains exploded when the bullet hit. Just like that, Charlie had ended a man's life. In all his years of studying math, he'd never found a solution this elegant, complete. He felt a sense of calm wash over him. It was the same satisfaction he felt every time he solved a difficult equation, only multiplied by a thousand. Nothing could compare to that feeling. Nothing but killing could bring about that level of response.
Now he stared at his seventh victim, huddled on the floor, begging Charlie not to do this. It was too late. Charlie couldn't change the equation at this point. There was only one outcome.
Charlie knew the FBI was looking for him. They would never catch him. He'd consulted for them on too many cases. He knew their methods. Hell, he'd helped write their playbook. They couldn't stop him. Charlie would kill this man. Don would find the body. He'd find Charlie's fingerprints and DNA. He'd know his brother had killed again.
Taking a deep breath, Charlie prepared to fire the weapon. He was ready to feel the euphoria. The few seconds right after he pulled the trigger were the most potent. Watching the body slump to the ground, the pool of blood slowly spread away from entry wound. Charlie couldn't wait to experience it again. And he would in three…
Two…
One…
"Charlie."
Charlie looked up. Don walked toward him. He wore his vest, the letters FBI practically glowing in the dim light. He held his gun pointed at Charlie.
"Charlie, don't do this," Don said. "Don't make me do this. Just put the gun down."
"Don?"
Charlie's thoughts began to swirl. What had been complete control seconds ago was spiraling into chaos. He looked at the man, sobbing at his feet. He felt the cold metal of the gun in his fingers. He calculated what Don's presence meant to the equation.
It meant he'd miscalculated somewhere along the way.
It meant Don had figured out Charlie's pattern.
It meant Charlie may never get the feeling from killing again.
"How did you find me?" Charlie asked. "It's impossible. I calculated for every outcome. No one should be able to predict I'd be here."
"You forgot one important factor."
Charlie thought through the math. There was no way he'd forgotten anything. Even if Don had found another mathematician, no one could have deciphered the pattern so fast. Charlie had been too careful.
"What did I forget?" he asked, still pointing his gun at his victim.
"Put down the gun and I'll tell you."
Typical Don.
"I can't," Charlie said. "I have to do this."
"No, Charlie. You have to put down the gun."
"You don't understand." For the first time, Charlie's voice shook.
"Help me understand, Charlie. Explain it to me. Two months ago you were forced to kill a man to protect me. It wasn't your choice then. But every death after that is on you. Why? Tell me. I'm listening."
What did Don think? That this was some stupid cry for attention?
"Why didn't you ever tell me?" Charlie asked quietly.
"Tell you what, buddy?"
The nickname made Charlie jump so bad that for the first time since that first kill, his hands shook. He took a breath and his hands steadied once more.
"Why didn't you tell me how it feels to kill? You've shot suspects before. You know the feeling."
"The guilt?" Don asked. He was still moving forward. Charlie calculated the distance and time it would take for Don to reach him. He would have to pull the trigger soon.
"The ecstasy," Charlie replied. "It's addicting, Donnie. I need it. I can't stop."
That made Don freeze in his tracks.
Charlie suspected the rest of Don's team was nearby along with half of the LAPD. Megan, David, and Colby would be covering the escape routes. Now that the FBI had caught up with him, Charlie would have a difficult time getting away. Even if he did, Don would find him again unless Charlie could figure out the weakness in his equation.
"Put down the gun, Charlie," Don said. "I'm not going to tell you again."
"Are you going to shoot me, Don?" Charlie asked.
"Only if you make me," Don replied.
"You would kill me to protect a stranger. That's funny. Two months ago I had to choose between my brother and a stranger. I chose my brother. Nice to see where your loyalties lie."
Don took another step closer. "I'm trying to save both of you. Give me the gun, Charlie. Let me help you."
"I don't want your help," Charlie said, but he noticed his hands were shaking again. "I can't be helped."
By now Don was close enough that he took one hand off his weapon and held it out for Charlie.
"Just give me the gun, Charlie. We'll figure this out."
Charlie would go to prison. Hell, six kills would earn him the death penalty. He'd never factored in those consequences when he started this. He'd never planned on Don catching him. Now he had to know why. The need to know how Don had figured out his pattern overcame his desire to kill.
"You promise to tell me how you found me," Charlie said. He could feel his resolve failing.
"I promise, buddy. Just give me the gun."
His hands were shaking so bad, he didn't trust himself to move. He stared at the gun trembling in his fingers. Then Don's hand appeared, slowly removing the weapon from Charlie's grasp. He heard Don mutter, "Clear," and strong arms grabbed him from behind.
"You promised!" Charlie screamed as he was forced to the ground, metal handcuffs restraining his arms from behind. "You promised, Donnie!"
Don and Megan knelt over the victim, speaking comforting words. No one spoke to Charlie. No one comforted Charlie as he lay face down on the cold cement floor.
"DON!" Charlie screamed again, earning a glance from his brother. The shaking had spread from his hands and now his entire body trembled with rage and fear.
At last Megan escorted the victim away and Don knelt by his brother.
"You want to know how I caught you?" Don asked. His voice was cold now. "You may be a genius, Charlie. You may have gone on killing for years if not for one thing."
"What?" Charlie gasped. Not knowing was unbearable.
Don's face changed. His eyes softened. He reached out a hand and touched his brother's curls.
"You forgot that you're my brother," Don said. "I know you better than anyone."
He didn't explain further, but straightened and walked away.
Charlie watched him go. Instead of his mind buzzing with the new information, his thoughts were blank. He felt numb. He barely heard the officer speaking to him, telling him something about remaining silent.
As Charlie was hauled to his feet, he sought out Don, but his brother had disappeared. Only LAPD officers stood around Charlie, gripping his arms as they dragged him toward an exit.
Charlie stopped walking, forcing the officers to pause.
"Tell my brother," Charlie began but choked on the words. He took a breath and tried again. "Tell my brother that I never forgot him."
It was the last thing Charlie said before the officers placed him in a vehicle and drove off. Charlie hadn't seen Don standing in the shadows, head bowed, hands shaking, listening to those final words.
- O -
Author's note: I'm still working on my Num3rs/Criminal Minds crossover, but I couldn't get this story out of my head. The idea of Charlie turning to the dark side was too tempting to resist.