"This is it then?" Kurt asked. Sans had sent an owl to Kurt the previous day. Now, only a bright, warm, late June Sunday, they were in the underground again. With any luck, they would come back with a third member, though how he would fit in the machine Kurt hadn't quite worked out yet.

"i think so," Sans said, passing Kurt a sheet of calculations.

Kurt double checked the skeleton's figures. "Why are these numbers so close to the ones you have listed for our home timeline? The rest of them were miles apart."
"i think they are our home timeline, one of them, anyway. i'm pretty sure this is one of the timelines that frisk, our frisk, went through when trying to find a way to save asriel. she told me, back in september, that she saw Doctor Gaster on one of his loops. hopefully, we end up in the same spot."

Kurt looked down again at the paper Sans at given him. "Waterfall, huh? Guess we better get moving then. We can take the boat from Hotland, right?"

"yeah, guess so," Sans agreed.

They took the machine down Alphys's elevator, through the lab, and to the Hotland dock. "Sans," Kurt said, "When we get there, what are we actually going to do? You postulated that he somehow exploded his soul into these hands of his. But how will we get it back out of them to him?

"don't know," Sans admitted. "i'm hoping that once we find him, we'll come up with something."

"That doesn't sound very encouraging," Kurt said, as he began to load the machine onto the boat person's boat. He was struck momentarily by the fact the monster always seemed to be exactly where they needed the boat to be. He pushed that aside. "Do you have any real idea?"

"i really don't," Sans apologized. "there's really only one way to find out,"

"I guess, but it doesn't make me feel confident." The boat slowly moved through the water. The boatmaster, normally a purveyor of esoteric wisdom, only hummed as they went up the river to the river dock. They unloaded the machine, and Sans led him down a path. Sans was unusually quiet, not saying anything as they continued.

"Uh, Sans?" Kurt said.

Sans kept walking, and only stopped when Kurt grabbed his bony shoulder blade. "hmmm?" Sans asked. "oh." In front of them was a gap in the road, with a stream running through it. It was one that Kurt probably would have been able to jump, if he'd had too. But trying to get the machine over it with a simple levitation and locomotion spell might prove disastrous.

"forgot about that," Sans said. He looked around briefly. "used to be a bird here. he got paid to take you over this gap. uh, don't suppose you know a way over this."

"Not without a magic carpet," Kurt said. "Yes, they exist. But they're banned in Britain, too much of a risk getting exposed. They can't fly as high as a broom without getting wet and threatening to fall apart. In drier areas, they work just fine, but not here. There is a flying charm, but that's something beyond even NEWT level, and the only person I know that's possibly mastered it is Dumbledore. We need some other way across."

"good thing i came prepared then," Sans told him. He shuffled through his pockets, producing several groups of large seeds. He leaned over and threw four of them in the water. The floated into the cavern wall, creating a line of flowers, that then opened up. He repeated this a few times, using each new row of blossoms to progress a bit further. "all good,"

"Huh," Kurt said, testing his weight cautiously on the first of the blossom, and it held. He even pushed pretty heavily, and was still supported. "What are those?" he asked, as he put the machine back into motion.

"bridge seeds," Sans told him. "Don't last a long time, but really handy things in the underground."

"I'll say," Kurt said, too impressed at the seeds to be grumpy at Sans trolling him again. "I can only imagine herbologists getting their hands on those."

"king asgore's been growing them to share topside," sans told him. "anyway, we're almost there."

As it turns out, 'there' was a small cave with a small table on it. Kurt walked over to examine it. "Is that a piece of cheese? Trapped in some sort of crystal? Where did that come from?"

"some mysteries are beyond even me to solve," Sans said, grinning at him. "but here we are. let's set up the machine." They did, putting in those delicate parts, possibly for the last time. "one last trip, so grab your neuralyzer." he made a face. "eh, that one wasn't very good, but it doesn't matter. you ready to go?"

Kurt rolled his eyes, but they climbed in, and set the machine. As always, the world outside the window faded to black, then white. And, after a moment, faded back in. They got out of the machine, and Kurt waited as Sans to perform his now usual phone checking ritual. "What have you learned?" Kurt asked the skeleton.

"nobody's seen frisk recently. Papyrus is saying something about thinking she might be in trouble, and we should keep the king from fighting... oh. we're then. we ought to be careful, don't want flowey to grab our souls, too."

"What?" asked Kurt, shocked. "What do you mean by that?"

"time for explanations later. time for moving right now. this room should be safe," Sans assured him. He led them back the way they had come.

This was initially disconcerting to Kurt, as the cavern corridor seemed longer, much longer than when they'd been in it in their own time line. It only grew more disconcerting with the presence of a door, a grey stone door. It absolutely had not been there before.

Sans opened the door, walking inside. "shut the door behind you. the stone should keep us safe from six-souled flowey."

Kurt did, but it had the effect of turning the entire room pitch dark, the only thing visible was Sans's eyelights. He pulled out his wand, lighting it with Lumos, and followed behind Sans. The interior cavern wasn't that big. It was only a small room, and it didn't go anywhere. But it was the being in the center of it that caused a chill to go down Kurt's spine.

Standing there, staring forward, possibly at Kurt, was a ghostly figure. It might have been a skeleton, but there were cracks, even missing pieces of the skull, causing his eye sockets to look deformed, and even stranger. It was wearing a black, almost wizard like lab coat.

But the change in Sans was making it worth it.

"Dad," he said, even his voice changing. "Dad? Can you see me? It's me, Sansy."

The skeleton just continued to stare at, or even through, his son. Sans reached up to try to take him in the arm. But he wasn't able to, his hand simply passed through the apparently opaque mysterious figure. "No," whispered Sans. "Dad. Gaster! It's me..." He tried again to take hold of the figure, but again, his hand found nothing there.

The figure just stared for another minute or two. Then, without warning, his eyes opened wide, and eyelights ignited, focusing on Sans. Only those eyelights moved, the rest of the apparition was immobile.

"Dad, I found them. I had to work really hard for them, but I found them." He pulled, still in the plastic he'd used to carry them, the four hands they'd collected from across different times, possibly different worlds.

The apparition spoke, at least. Its mouth moved. The noise it made was so layered that Kurt couldn't actually make out what he said. It was like it was both echoing from a great distance away and not actually fading, resulting in an unintelligible cacophony of sound. Sans didn't react to the noise, but tried to take the apparition's sleeve a third time, again to no effect.

It knelt, more or less, studying the hands they'd collected. Its eyes grew wide again, and it began to glide toward the door, only to be stopped by Sans's shout of "NO!" It turned back, studying Sans again.

Sans had his phone out. "Not yet, Flowey's about to pull every soul in the underground. We can't go anywhere until he's done with that."

They waited, Kurt rather uncomfortable. "Sans? Do you even know where he might have been going?"

The apparition's eyelights burned in Kurt's direction, and he tried again to communicate. But to no greater effect. Finally, to at least apparent apprehension, the specter pulled a hand (that had a hole in it, adding to the shock value) from his coat, pointed to itself, then to the floor.

"Your lab," Sans said. "What's in..." Sans eyelights glinted. "Of course. That is in your lab."

"What's in his lab?" Kurt asked.

Sans looked at his phone again. "Alphys just woke up, must be safe to go now. Come on."

The apparition left first, right through the door. Sans and Kurt left the more normal way. Sans stared after the apparition, watching him leave. He turned back to Kurt. "come on. everyone from snowden will be taking the boat. we can leave the machine there. we'll take a shortcut."

"What?" Kurt asked, as Sans took Kurt's hand in his bones.

"don't worry," Sans said. "i know plenty of shortcuts."

Kurt had been in Alphys's lab before, at least in passing. But he'd never taken the elevator down. He hadn't even known there was an elevator. The area was dark, and rather foreboding looking. It actually reminded him of the days when he had to work late in the Ministry, when everyone else had gone home, and the lights had been turned down, but the machines kept on turning. It was the same kind of ominous feeling he had gotten when he'd first started working.

Sans led him out of the elevator, around a corner, and into a dormitory, of sorts. The apparition was waiting for them, hovering near one of the beds. Down another corridor, and... "What is that?" Kurt asked.

This time, "That" looked like a large demonic, goat's head. It had large wires suspending it over a pit. Sans went over to a panel on the wall, and expertly manipulated it. The machine lit up, giving it the impression of glowing eyes. A small platform emerged from the depths, putting it right under the 'mouth' of the large device.

"step one," Sans said. He took out the hands they'd collected, putting them on the platform's device. "draw the determination, the soul, out from these pieces. eh, step back, kurt."

Kurt stepped back, as the machine activate. A small, needle-like protrusion came from the 'mouth' of the Determination Extractor. The hands... bubbled... for the lack of a better term, before going inert again. Sans turned the machine off.

"step two, and i never thought i'd be saying this," Sans said, his eyelights glinting. "but i actually will need to reverse the polarity of this thing, and turn the determination extractor into a determination injector."

Kurt suddenly realized he'd heard of this before. "That, that's how Flowey got created, right? The scientist, whatever her name was, when alphys injected determination drawn from the fallen human souls, into a flower that had been unknowingly coated with Asriel's dust? Wait, wait. Why can't you just give him a jab with a regular needle?"

"monster souls are a bit... weaker, there's less to them than a human soul. one of the purposes of the experiment was to find out why. i don't want to risk losing any part of Gaster's soul. here. give me a hand with this," Sans said.

They worked for a good fifteen minutes, turning around certain key components. Sans doing something called 'reprogramming' to others. The apparition watched them, giving commentary in the same unintelligible language he'd used previously. Eventually both skeletons were satisfied with the changes, and the apparition floated to the platform.

"you okay there, Dad?" Sans asked.

Could a floating apparition of a skeleton look nervous? This one didn't seem to. On the other hand, Sans didn't look nervous either, but Kurt had been around his friend long enough to know he was. Would this work? The idea of someone being able to recover a soul was thrilling to Kurt. This was magic he could bring to the department of mysteries. The completely new art of soul magic, and this was a way to research it!

The voice answered. Kurt wasn't sure it was an affirmative answer, but it was an answer. Sans looked for a few more seconds, then flipped the switch again.

Once again, the machine flared to life, the needle-like protusion extending again, piercing the now uncovered bone of the apparition. He screamed. This time Kurt was sure of it. The scream was so loud, so discordant, and he had to clap his hands over his ears.

And, after a few seconds, the noise began to fade. Kurt looked up, and saw the apparition itself was fading. Fading right out of reality! "Sans!"

But Sans was too shocked to move. He didn't manage to turn off the machine until Doctor Gaster was well and truly gone. When finally did, he didn't shout, he didn't scream. He just stared. Blank eyes, with no eyelights, focused on spot Gaster had been just a moment earlier.

Kurt walked over to his friend, and put his arm around the Skeleton's shoulder blades. "I'm sorry."

Sans didn't respond. He wiped his eyes.

"You still have a brother that needs to know you're alright, Sans. Let's go home. We can tell him everything."

"Papyrus doesn't remember Gaster. he'd be happier staying that way."

"Papyrus needs to know that his brother is alright, and why he is depressed," Kurt insisted. "Come on. Let's go back to the machine."

Wordlessly, Sans slipped from Kurt, going to retrieve Gaster's hands. Then he looked up at the wizard, eyelights still out, and nodded.

The trip back to the machine was long, and quiet. Sans had no interest in trying the short cuts. Kurt had to wear the disillusionment cloak through part of Hotland, though they managed to catch the riverperson going back down to Snowden to pick up another group of individuals streaming towards the barrier. The machine was right where they left it, as Sans had predicted.

For a change, Kurt got in the driver side, and plugged in the numbers for home. He double, then triple checked them, and activated the machine. After the normal rumbles and fade outs, they returned to their home timeline. Sans made no move to get out of the machine.

"At least you freed him from limbo," Kurt tried. "He's at peace now. Come on. Let's go put the machine away. I'll apparate you home. No need to walk. But you can't just give up on life. People need you."

Sans didn't respond, though something in his pocket gave a musical chirp.

"Sans, I'm serious," Kurt pulled himself out of the machine, walked around it, and opened the Sans-side door. "Come on. Or I'll locomotor the machine with you still in it. That won't be comfortable."

Sans let loose an audible sigh, as the thing in his pocket gave a second chirp, but stood up. They began the trek back to the Waterfall dock, when Sans's pocket chirped a third time. Sans grumbled, and pulled up his phone, scrolling with a bony finger.

Then he stopped.

"Come on, Sans," Kurt told him. "I'm going to tell your brother if you don't."

"she remembers him," he said quietly.

"What was that?" Kurt asked.

"you know, despite replacing him, and finishing his determination experiment with the flower he picked out, i haven't thought of Gaster in a long time. found myself thinking about him just now. i miss the old doctor. anyone thought about him recently? sans? you worked with him too, do you remember any other experiments i don't?" Sans read aloud. "that's from alphys. she remembers him. There's a few other comments, from torii and asgore, but..."

Then Sans's phone began to ring. He held it up to his ear as his phone, and for the first time since they'd left the True Lab, his eyelights reignited. "yeah, bro?"

"Sans!" came the voice on the other end of the phone. "I was just thinking about dad. I haven't thought about him in a long time. Sans, you worked in the lab with him. What actually happened?"

"i don't know, Papyrus," Sans said. "i wasn't there when it happened, remember? wait... wait... could it be? kurt? we need to get to the true labs, now!" Hanging up the phone, he dragged Kurt quicker than he normally would have walked down to the dock. Waiting only momentarily for Kurt to load the machine onto the boat, he asked to be taken to Hotland.

They abandoned the machine on the Hotland dock (and Sans's phone rang again, but he ignored it), and raced into Alphys's lab, and down the elevator. At the determination extractor, they stopped. And they stared.

"I must admit, that hurt," said a slightly ethereal voice from ahead of them. "I think it caused me to black out. Fascinating. Where and when am I, anyway? Where did they..." Doctor Gaster turned at the sound of rushing footsteps. "Sans?"

Sans bodily pulled down the larger skeleton into a violent embrace. "Dad, it did work. It did work!"

"It did, my Sansy. My son. I was watching the whole time, you know. I saw how you tried to get my possibility machine working."

"it didn't work until..."

"I know, I know," Gaster said, patting his son's shoulder blade. "But you kept it stable, and didn't let your curiosity get the better of you, like I let mine."

"i gave up."

"Sometimes things really are impossible, Sans. You realized that where I did not. Which meant you were there when your brother needed you. Like I was not. Then, when the saviour of the underground needed you, you were there for her, too. When she brought the very thing you needed to finish the machine, you didn't think of yourself first. You thought of your friends. Sans, I could not be prouder of you." And he returned Sans hug. "I promise, I will never do that again. I prefer to keep both my feet in a single possibility, from here on out."

After a minute, they finally released each other. "And you, master wizard. I may not have been able to see past the underground, but I know I have you to thank for the rescue." He put out a bony hand, and Kurt took it to shake. "I feel embarrassed to admit this, but I don't know your name."

Sans's phone rang again. He looked at it, and his eyelights glinted.

"hey, Papyrus,"

"Sans! You hung up on me! How lazy can you get? I ask you a simple question and this is how you..."

"bro," Sans interrupted, "someone here would like to speak to you." He handed the phone to Dr. Gaster.

"Hello, Papyrus," the Doctor said.

There was silence on the other end. Nobody needed to tell Kurt how unusual that was. Papyrus was never caught for lack of words.

"Hello? Are you still there, Papyrus?" Gaster asked.

"Dad?"