Well, this is it. I've finally officially completed my first multichapter fanfic! Thanks to everyone for all the support. I can't say I have any more fanfics solely of the Who variety currently in the works—certainly won't be starting any other projects of this size anytime soon—but you just might be seeing more of me in the future. Either way, I hope this ending puts as nice a bow on everything as I think it does. Do enjoy the seventeenth and final installment of On the Brink of Nothing.

Donna felt grossly underqualified to be the one supervising the transport of Algara down to the caves, but there wasn't really all that much she had to do.

It was close to the time Algara's sight would fail her completely; bringing her down when she was still fairly able to walk by herself was safest. She sat on the cave floor with her family, surrounded by lizards, and the crowd of Upper Cirulians who had wanted to see the transfer hung back watching.

Hours passed, and Donna very nearly fell asleep sitting against the cave wall, but she would just splash some water into her face and walk some laps around the area as many times as was necessary. Finally, Algara went totally unresponsive, and the small creature detached itself from her arm and moved with surprising speed across the cave floor to where the craftsmen were waiting.

She would remember the transfer as… unremarkable. It was faster than the draining process, but still took a couple hours, during which the Doctor arrived along with a handful of Upper Cirulians. After that, paying attention became all the more difficult. When she looked back on it, she could recall only a flurry of activity in the general vicinity of the craftsmen, the Doctor describing his own adventure with Tuln—all she could remember specifically was that the Cirulian had turned terrified near the end, but managed to stick resolutely to his promise—and their return to the TARDIS. She'd gone straight to her bedroom and intended to change into her nightclothes, but when she woke up she found that all she'd actually done was kick off her shoes.

She sat there in bed, staring at the dusty trainers across the room and wondering how long she'd slept. Her bracelet was currently a grassy green, the next colour in the cycle after yellow, so it couldn't have been too long.

Where was the Doctor?

Donna sighed silently. He certainly needed to be checked up on and told what still needed doing to maintain his own well-being, but he could probably make it for another half hour while she washed up.

Donna passed from the hallway and into the console room wearing a clean shirt and jeans, a warm sweater, and comfortable shoes suitable for hiking—just in case. Her hair was still damp from her shower but she was perfectly warm and ready to tackle another day, though there was a conversation that needed to take place before anything else happened.

As she'd fully expected, the Doctor was flying about the console, making constant adjustments to the controls. When she appeared, he crowed, "Morning, sleepyhead!" To punctuate this greeting, he flipped a large switch on the wall upwards, producing an impressive clang. Donna looked about, wondering what he'd been doing while she slept. Hopefully gotten some rest himself. He seemed in perfectly good health—his movements were certain and steady, his face clean, his eyes bright as ever. Even his skin seemed to have regained some glow it had lost along the way.

She supposed he'd known by some security system in the TARDIS alerting him of her approach—he always seemed to know she was coming whenever she entered the console room. She stood at the edge of the room, watching him fly about the mass of buttons and switches and levers and screens and dials, and asked, "How long've you been at this?"

"Just started. So! Yesterday we went for hills and got a whole lot more than we bargained for—I was thinking today we aim a lot higher. Namely, Messala-9's clouds! Cloud restaurants, can you imagine? You can eat in a station that's suspended in the troposphere and watch the rain form and fall, which, by the way—"

"Doctor," Donna said, exasperated. "What were you doing while I slept? Did Cirula turn out okay?"

"Oh yeah," he replied without missing a beat. "They eventually got a system in place, loads of paperwork involved in donations, they came to benefit massively from the advances made by the cavers, and the cavers? They got to move up and out. See the sun. Feel the wind, the grass. Eat comparatively gourmet meals every single day." He sighed softly. "I'll tell you what, I'm going to be producing a lot of sensory descriptions in the coming weeks. I think it'll be a good exercise and I encourage you to try it as well."

Donna shrugged and nodded at the same time.

"Some of them died from exposure," he went on, continuing to fiddle with the controls. "Their bodies weren't really prepared for the shift. But every individual made their choice to move, and for them, it was worth it. And as we've seen ample evidence of, they as a species can adapt quickly." He frowned at a screen, tapped it twice with his index finger, and pushed half a dozen buttons before he continued speaking. "There were the other colonies, of course, and they found some of them—utilising the map I drew up for them based on what the gatherers told me—and used members from the original one we helped to tell them the situation, but keeping them stocked with senses wasn't easy. There were often not enough volunteers. Then when the technological age came they found ways to communicate with and travel to other communities much more easily, and it took a couple hundred years and assistance from some visiting Koaimans but they even managed to develop this device that allowed the senseless people to communicate mind-to-mind. Really amazing leaps they made, in not that much time. I tell you what, once they made the transition they really knew what to focus on. A surprisingly impressive species, the Upper Cirulians. I once read about this race that—"

"Are your senses back?"

He stopped short, and looked up at her. "Of course. They kept their end of the bargain."

She eyed his covered arms meaningfully. "Can I see?"

He blinked, and after a moment straightened up from his position hunching over the console, compliantly shedding his jacket and rolling up his sleeves. Sure enough, his arms were bare. Donna didn't even see any faded red suction marks, as she'd half-expected. A smile spread across her face of its own accord.

"To be honest," the Doctor said, pulling his sleeves back down, "the first thing I did after you struck off for your room was eat about two full meals' worth of food. Felt a bit sick, but it was fantastic. And you're probably quite hungry too, so Messala-9? Clouds? Literal pie in the sky? Or at least something vaguely pie-like."

"We're not done talking about this," she said firmly. "What did they do to you?"

He stopped halfway through getting back into his jacket, and met her eyes, appearing mildly alarmed and genuinely confused. "What?"

"When the rest of us were experiencing their history. What happened to you that shook you up so much?"

He was silent for a few moments—just a few. "Exactly the same as what happened to you."

"Oh, don't give me that," she snorted. "You're certainly a drama queen but I can't quite picturing you reacting like… like you did, when seriously everyone else was already more or less stable by the time you came to your senses."

"The reason for 'coming to your senses'—not sure whether that euphemism is apter than ever here or just serves to make things more confusing—was some part of your brain realizing that you'd absorbed all you could handle from the experience for the time being. You knew, on some level, that if it continued, either you'd overload and shut down or it would just be useless and you wouldn't be able to process the excess memories later on. So you came out of it. I hadn't yet reached that point."

"Your capacity was greater than the rest of ours?" she said dubiously. It made sense, and she could swallow it, but she was sure there was more to it than that.

"Yes." He paused, and shrugged. "As well as… Well. You remember how I have a sixth sense? The same one that all the lauep are born with?"

"Yeah," she said uncertainly.

"And how in the case of the craftsmen, their minds are positively buzzing with ideas from the moment they're old enough to think, but that one sense is their only outlet for such thoughts?"

"Yeah," she said again, the connection slowly becoming clearer to her.

"And how those sensations and messages would be the most numerous, because they're the only ones guaranteed for all craftsmen, for the duration of their lives? And how while you and the Upper Cirulians weren't equipped to fully comprehend the experiences of those sensations across generations, I was?"

"Doctor," said Donna softly.

"I'm fine, really I am. It just… well. It was a lot to take in, and it took a bit more time, that's all."

She wasn't sure whether to believe him. Best not, she decided, and fixed him with a hard glare.

He held up his hands, palms facing outwards. "What? I mean it. You want me to try to explain it? I don't really know how."

She crossed her arms. "Explaining things is your specialty, innit?"

He stared at her for a moment, and sighed, running a hand through his hair, which was once again styled just as it usually was, and sprang back up into action once he took his hand down. "Gallifreyan is so much better equipped to explain this sort of thing than English is. It's like…" He licked his lips, thinking. "When there's someone in your mind, you can tell that something's wrong, and you have the limited capacity to receive and respond to messages, but…" He shook his head. "It was overwhelming. It was like… Well, how was it for you?"

Donna blinked, surprised at the question, and shrugged without uncrossing her arms. "It was too much. It was like… like I was surrounded by scenes playing from all throughout history and I had to be looking at at least one of them at any given time, but I couldn't… I couldn't keep up with the changes, and I couldn't keep track of all the input, and I knew that there would be a lot I wouldn't be able to remember."

"Okay," he said. "So… imagine how many craftsmen's memories we were experiencing. I don't even know the number, but it's a lot. Now imagine that rather than a mass of memories whose origins you can't keep track of, it's a multitude of individual sets of memories, whole lives, and you have no filter to keep yourself from experiencing all of it at the same time."

She blinked at him, trying to comply, trying to imagine. It was impossible. It sounded bloody awful, but it was also so completely different from anything she'd ever known that… she just couldn't picture it. She'd try, but find herself disappointingly detached from it all.

But even if she couldn't place herself in the situation, she could certainly do so with him, and he was standing in front of her with that air of unconcern that usually meant he really was quite bothered, and all she could do was double check: "But you're okay?"

He smiled, and she thought she saw a hint of relief in there—how shocking, he didn't want to be talking about this. "Always. In the moment I realize it may have looked bad, but it really honestly wasn't."

This time, Donna added silently, because she knew he never would—not with the implications those words carried.

"One more thing," she said, and the Doctor nodded as he finally picked his jacket back up and slipped into it. "What happened to Ilseg?"

He furrowed his brow. "What 'happened' to him? Well I didn't see him mentioned in any of the history books or articles I read except to describe how he was involved in the negotiations, if that's what you mean."

She frowned, in fact not quite sure what she'd been hoping to hear. "Did you talk to him before we left?"

"Briefly." He scratched his head, clearly intending to continue but unsure of what to say. "He… he was not in the best of sorts, to put it mildly. But I do think he's going to be okay."

Donna regarded him dubiously. She could just imagine how that conversation would have gone… She was also absolutely sure that the Doctor would not repeat any part of it.

"I know enough to recognize the signs of a father who's lost a child."

He was back to messing with the controls, clearly having lost interest in the topic—or at least become unwilling to pursue it further. She didn't let the silence go on for too long before asking, "Anything else you wanted to talk about?"

He was leaning over the console, putting almost his whole body into the stretch as he tried to reach a poorly-placed switch. "Not really," he replied, voice mildly strained, and managed to flip the switch up with the tip of his finger, bouncing back immediately and straightening his jacket. "Ha-hah! Now then, you don't seem to have much interest in Messala-9; was there something else you had in mind?"

Donna started to shake her head, but mere moments into the gesture stopped short. "Actually…" She chewed the inside of her cheek thoughtfully. "Can we just… stop at the nearest inhabited planet and… see what they've got in the way of food? Find somewhere quiet and pretty and just eat there?"

He looked at her strangely. "You know by now that the TARDIS travels through time and space, right? Nearness doesn't have to be a factor when choosing destinations."

"I do know that," she said, fixing him with an uncompromising stare.

He tilted his head, and checked out a monitor. "The nearest planet's Linth. Pretty big, pretty dry, sparsely populated. Fairly flat. I've heard some good things about its biggest mountain range, I suppose…"

Donna smiled. "Sounds perfect."

He observed her thoughtfully for a few moments, and she held still, meeting his eyes evenly. It wasn't long before he shrugged, and spun around, returning to the mad mess that was the control center of the TARDIS. "Right then! I'll find Linth's most delicious dish and most spectacular attraction. Probably just a scenic mountaintop, but to tell you the truth, at the moment being high above the ground sounds pretty good to me."

"Better than caves?"

He nodded, the corner of his mouth curving upward. "Better than caves."

Donna tilted her head, unsure whether his shoulders had just sagged a bit or she was imagining things. "Been a rough day for you, huh?" she said softly.

"Nonsense. I don't have rough days. Plus you've been asleep for long enough that that incomplete manifestation of the present perfect isn't really accurate anymore."

She regarded him with that fond concern she'd become so comfortable in, and he continued whizzing about the console in that ignoring-the-issue carefully carefree way he'd already been comfortable in by the time she'd met him. She tried to remember how he'd appeared not so long before, when he'd been cut off in almost every way from the world, when he'd temporarily lost his ability to see and teach and learn… to be the Doctor. Already it seemed so far away. A tired smile found its way onto her face.

Nothing had changed.

And nothing ever would.