Toronto, Canada: 2002 AD.

Natalie sat silently in her living room watching Nick nervously pace back and forth in front of the window. He'd shown up unexpectedly, and by the grim look on his face, Natalie knew he'd made his decision.

Finally, he stopped and looked down at her. Once before they'd been in this same position, he standing by the window, she sitting on the sofa looking up at him. Then, they had begun a new chapter in their lives. Now, she knew he was here to say good-bye.

"We have to talk," he began.

Natalie nodded slowly. "Sit down," she said, indicating the space on the sofa next to her. He looked unsure for a moment, then reluctantly moved toward her. After he was seated, he reached over and took her hand.

"I've been in Toronto for fifteen years," he whispered after a few moments.

Natalie looked away, her eyes suddenly stinging. She'd been right. She'd seen this coming. "You have to go away," she said after a time, her voice tight and brittle.

His hand on hers tightened just a little. "I've stayed longer than I should have," he said quickly. "I don't want to go but . . ."

"But you can't stay," she finished for him. "Schanke asked you just last week what your secret to eternal youth was," she reminded him.

"Imagine what he'd say if he found out what it was," Nick said, with a bitter laugh.

"What are you going to say to him?"

Nick shrugged. "I'll keep it vague." Then he was silent, staring down intently at their clasped hands. She watched his face carefully, knowing that Schanke would receive the occasional postcard or letter, and a few Christmas cards, but over time they would gradually taper off.

"When--when you get settled, you'll let me know that you're all right?" she asked. Better to be practical about this. It was easier that way.

His head snapped up, and he took a deep breath, opening his mouth to speak. Natalie stared into his eyes, and she suddenly knew the question he was going to ask. But before he could speak, she lifted her hand quickly and pressed her fingers gently against his lips, shaking her head. "Please don't ask," she whispered. "Because right now, at this moment, I just might take you up on it." She paused, realizing that her eyes were filling with tears. "But we both know I can't go with you."

She saw understanding and regret in his eyes as he looked back at her, and he slowly nodded. "I'm sorry," he whispered.

"Don't be," Natalie said simply. "But you can do two things for me," she said.

"Name them."

Natalie paused and took a deep breath. "I'll need to take a lot of samples," she said. "So that I have something to work with."

He stared back at her, his expression a mixture of amazement and amusement, and the barest traces of sadness. But Natalie was not about to apologize now for being practical, not after all this time. Finally he nodded. "And the second thing?" he asked.

"The samples won't last long, but on the chance I should find something, will I be able reach you?" The last was said tentatively, since she knew what she was really asking was whether or not he wanted to stay in touch with her.

He seemed to hesitate over this, but only for a moment. "I'll make sure you can reach me," he said softly. "If you ever need me for anything, you'll always know how to reach me," he promised.

"And," she continued, forcing the words out around the tightness in her chest and throat, "if you . . . find someone else who can help you, you'll let me know. I've--I've got a lot of data. You won't have to start from scratch, and--"

He silenced her by kissing her, twining one hand in her hair. It was a sad, desperate kiss, and Natalie wanted it to last forever.

But that was impossible, and when he reluctantly pulled away from her she rose, using the time it took to fetch her medical bag to pull herself together. This was hard enough as it was, and neither of them were making it any easier.

They were silent as she took her samples. She wasn't sure just when she'd started carrying around all these extra slides and vials, but she knew it had been recent. Some part of her had been preparing for his departure, she realized.

Finally, there was nothing more to do, and they'd somehow found their way to the door of her apartment.

"There's so much I want to say. This time, this place has been the happiest of my life," he said, taking her into his arms and holding her tight. "'Thank you' isn't enough," he said simply, and she realized he was shaking.

"It's enough," she said.

He kissed her again. "Be happy, Natalie," he said softly, his voice breaking.

Her arms tightened around him. "You too," she whispered softly. There was more, she wanted to say so much more, but the words wouldn't come. "Good-bye, Nick," she said instead.

And then, he was gone.