They never stopped running.
Their journeys were legion, as were the worlds and lives they saved. Their bodies aged, though his somewhat less than hers. Jack teased the Doctor about settling down, and flirted with Buffy every chance he got, even as she entered her seventies. They returned to Earth to play with Martha’s children, then the grandkids. Others came and went as the Doctor and the Slayer passed through, policing time and space.
Of course, they bickered, they disagreed, she died again on four separate occasions; he dumped her in the Selachia system for eighteen months to teach her a lesson about thinking before acting only to return to find she’d become a warrior queen; she left again a decade later when they disagreed over mercy and second chances, only to beg him for help rescuing her new home in the Silver Devastation while they fell in love again; the Master returned, several times, and life never approached anything normal. But for sixty years, it was mostly good.
Now she was sick, and he was terrified.
Buffy was never sick. But over the past few weeks, it had been as if she was fading out of life. Eighty years in a human body meant more than eighty for a Time Lord (people would now ask if she was his mother, and once, to her great amusement, his grandmother), yet she’d remained vital, time taking its toll only reluctantly: a line here or there, the silver of her hair, a figure just that much thinner, skin that grew ever more translucent. Every morning she still managed the same workout he’d watched her do nearly every morning for decades. He convinced himself that her Slayer healing meant she would be able to stay with him longer, that the end was not so inevitably nigh. In his tenth incarnation he would soon be a thousand years old, and he would meet that landmark with her at his side.
But then it started. Her mind would wander. Her strength would be there, then not. And the headaches: Buffy had had deaths less agonizing. Not one hospital across time or space could explain her condition. Over the past two weeks it all intensified, and as he nursed her, he began steeling himself for the end, and wondered if he would be able to say goodbye.
This morning he awoke to find her not in bed. It had been five days since she’d last struggled out. He put on his dressing gown and searched the TARDIS, finding her in the console room. “You’re up,” he said, with a hopeful smile. Her eyes held his gaze, and to his relief they were lucid, and she was smiling at him, and relief washed over him as he exhaled the breath he hadn’t realized he’d held. Buffy beckoned him with a tiny finger, and he joined her by the monitor.
“It found me.” The panel showed a massive surge of power piercing through space-time. The Doctor couldn’t contain his shock as he examined the readings.
“What?! No, no, no. It’s not the same thing at all. That was a sledgehammer. This, this is like a hypodermic needle. What the hell is it? What do you mean that it found you?”
“I don’t know. All I know is that these past weeks, I’ve felt pulled. Stretched like a piece of gum. Now that the TARDIS is here, I’m fine, but the pull is incredible, Doctor. I’m not sure, but it feels familiar. I think it may be Willow. I think she may have found me.”
“No. No. There’s no way to get that power. And it’s been sixty years. You belong here. You’re going to stay with me and you’ll get better, and we’ll take a vacation in New New New New New New New New New New New New New San Diego. We’ll go to the beach, and I’ll tell you all about my days at U.N.I.T. and you’ll feed me Jelly Babies and tease me about the huge fool I make of myself at karaoke night and it will be just as beautiful and perfect as it ever was.” He pulled her closer to him.
“I don’t think we have a choice. We hardly ever do. But I love you, Doctor. I always loved you.”
“No. No. You wouldn’t let me go. I won’t let you. We’ll be light years away in a second.”
“I don’t want to either. But I already feel lighter.” The Doctor watched in horror.
“You’re phasing out of this dimension! You knew? But you didn’t – you were going to let me sleep through it?”
“Shhh, we only have a few more minutes.” Her eyes took on that dreamy look they’d been locked in so often lately. “I wonder what eighty-year-old Willow will look like? I’ll get to see my sister again. It’ll be nice. My farewell tour home.” Buffy stroked his cheek as he clutched her gown, which remained solid.
“I’ll follow you, and I’ll make the farewell tour with you. I won’t let you go without me, Buffy.”
“What galaxy are you going to sacrifice to punch through? I remember, Doctor, remember every damn thing you’ve ever told me.”
“Coward.” She phased out completely for a second, and then returned. “Oh, Doctor. It’s so dark!”
Then she kissed him, and in that instant he memorized again the feel of her mouth and of her body as it pressed against him. And just like that, he found himself embracing the air. Her clothes piled at his feet as they fell through his fingers. The monitors read nothing out of the usual, just the TARDIS drifting through an unremarkable field of space. Later, the Doctor would calculate that it had been the position of Earth one day in the year 2001. But for now he groaned, and buried his face in her pajamas, reveling in the smell of her. After a few minutes he returned to the bedroom they had shared, replaced the clothes in the closet, and returned to bed.
Tomorrow he would get out the ladder and dismantle her nest in the rafters. He’d seal off this bedroom and move to another. Perhaps he would regenerate, and find some new adventure for his new self. Time marches on, so too must Time Lords.
Today he’d mourn Buffy Summers yet again. But he’d never stop looking for her.
It was so dark. From the arms of her love, she opened her eyes with a gasp, and saw only darkness.
Afterwards, after the coffin and the demons, Spike told her it had been one hundred forty-seven days and now a whole other lifetime lay in front of her. She felt cheated.
Once the Doctor had explained that, though he was the last of the Time Lords and could regenerate as many times as he desired, he believed there would come a time when the idea of another lifetime would be too exhausting, and he would finally let Death and surcease take him. She’d told him he was too vain to ever give up like that, and they’d made love and she’d hadn’t understood what he meant.
Now she was huddling away from the sunlight and her no-longer familiar friends of her youth, her returned youth, and poor Spike was staring at her with his puppy dog eyes, and he reminded her of the Doctor in those early days, when he treated her like some sort of holy artifact from another world, and it already felt as distant as a dream. Her heart broke again. She had to tell someone.
“I was happy. I was at peace. I was loved, and I was complete.”
Her throat closed. How could she explain the Doctor or her life with him?
“I think I was in heaven.”