She went straight home after the debrief. Grabbed her bag from her desk, took the lift down to the carpark, and drove straight home. She felt strangely detached during the drive, her hands turning the wheels mechanically, automatically, her feet tapping the brake and accelerator without conscious thought. It was a miracle that she didn't and up in a car accident.

A short while later, she found herself turning her key in the door of her apartment. She stepped inside, and placed her bag on the stool. Her hands only shook a little when she touched the cold metal of her gun. She set it down carefully on the countertop, along with her badge.

Glancing around the apartment, it felt foreign. But nothing had changed. The walls, the television, the couch, the coffee table - all exactly as she had left them.

But it was all a lie. Everything had changed.

That was the couch where she and Casey had spent many a night, with beer and conversation. It was where he had held her in his arms and let his cologne linger over her senses, where they had gazed into each other eyes - Casey had such beautiful eyes without the malignant glint of NZT, eyes that she would never see again. They had wished so fervently that they could see past the walls of secrets and into each other's hearts. But they'd never did. So that became the couch where she'd avoided Casey's gaze, gulped down mouthfuls of beer and tried to dodge the conversation about a romantic evening on the mountaintop. If only she had known, she would have gladly gone to the moon with him if it would save him. If only she had had the courage to speak the words she needed to say right then and there, if she had faced the music with the grit of the special agent that she was, maybe Casey would still be alive.

A knock on the door made Rebecca jump. She shook her head to clear her thoughts, realising that she'd been standing at the edge of her living room for some time, staring at the couch.

"Rebecca?" It was Brian.

Her movements were confident as she took two steps to reach the door and opened it. There he was in all his innocence, standing there in front of her. Alive.

Rebecca's next breath caught a little as she inhaled, but she ignored it. She opened the door wider, so that he would step in. "How're you doing?" Her voice was steady, not at all betraying the tightness in her throat. It wouldn't do to be vulnerable in front of Brian now. After all, he was the one that almost got shot in the head.

There was no trace of Brian's usual cheery class clown demeanour. His eyebrows were furrowed and his eyes gentle. There was no steely glint in them now; the day's NZT had worn off.

"I actually came to ask you that,' Brian said, as he stepped inside and took off his coat. "Just came from Boyle's, and thought I'd check on you." He paused and looked intently at Rebecca, like a botanist gazing critically at a plant specimen. "Glad I did, too."

Rebecca was still standing at the door, her hand resting on the doorknob after having closed it behind Brian. "I'm fine," she said, trying to sound reassuring. There was no quaver in her voice, no inkling of distress.

Brian raised his eyebrows. "You're crying," he pointed out gently.

Raising a hand to her cheek, Rebecca felt dampness beneath her fingers and realised he was right. When had she shed the tears? As her vision blurred with fresh tears, she felt Brian place his hands on her shoulders and guide her to the couch. She wiped away the tears impatiently.

"I'm fine, really," she said. "Just a little shaken by today's events, I guess."

Brian nodded. "Yeah."

A silence ensued. It wasn't the gentle, companionable silence that they often enjoyed. This one was heavy, thick with grief and sorrow and, most of all, guilt. It hovered above them, threatening to crush them, engulfing them as they each tried to compose their thoughts, desperately reaching through the tangle of emotions for some string of words that might offer both comfort and clarity.

Finally, it was Brian who spoke. His words cut through the heavy silence, as if creating a path to bridge the darkness between them. They weren't poetic, or filled with wisdom, or brimming with careful comfort. But they were honest. "Look, I don't know how you're feeling right now. Without NZT I don't even know how I'm feeling right now." He sighed, and half-nodded at Rebecca's bright eyes looking at him intently, taking in his every word. "You know, I never thought it was dangerous. Obviously, lots of dangerous stuff has happened as a result of it, but I never thought it could be so dangerous, like other drugs. But what happened to Casey today..." He trailed off, and there was a momentary pause, but he continued. "The thing about NZT is that it shows you all the possibilities. All the different ways something could end. But only if you're looking for them. It's both a blessing and a curse."

Brian had been looking straight ahead as he spoke, turning her head to Rebecca every now an then, but now he shifted on the couch and looked directly at her. "Even without NZT, I bet you're entertaining what could have happened differently." Her eyes dropped from his gaze for a moment, and he knew he was right, but she protested anyway.

"Boyle did what he had to do," Rebecca said firmly. "What he was trained to do."

Brian nodded. "But that's not what I meant. You're thinking of all the things you could have done differently. Things you said to him, or things you didn't say. When you said them, or didn't say them. I'm telling you now, as a friend, don't do it. Don't torture yourself over all the possibilities, because you know - you know - that there was no way you could have foreseen what happened today." Brian's eyes were positively burning with intensity now, as if he could burn his message into Rebecca's mind.

Rebecca took a deep breath and exhaled steadily. "Thank you," she said, her voice quiet and steady. Maybe if she could convince him she'd be fine, he was back down. She wasn't Brian's responsibility. She was his handler and she was supposed to be looking after him, not the other way around.

Brian sighed. "I know I can't convince you that it's not your fault. Even though you know, rationally, that you've done nothing wrong, I can't silence that little voice that whispers at the back of your mind. Guilt is funny like that." His voice sounded so defeated that she almost felt as if she'd start crying again. "And grief is too. Even if it didn't work out, I know you cared for him." He half-smiled and squeezed her hand gently - when had he started holding her hands? "Look, if you want to talk,I'm here to listen. Or if you want to just sit here, I'm up for that too. I'll bet the FBI has taught you to shove all those feelings into one corner of your brain, to compartmentalise them or whatever, but when the walls of that compartment wear thin, I just want you to know that I'm here for you."

She almost smiled. A little rapidly blinking dispersed the wetness around her eyes, and she squeezed his hand in return. "Thank you, Brian."

Without letting go of Rebecca's hand, Brian shifted on the couch again so that they were both comfortably seated, facing the television. This time, the silence was warm and comforting, like a blanket, and they simply sat and wandered through their labyrinths of thoughts.