A/N: This is my new Undertale Fanfiction I've begun working on alongside my MHA projects. Inspired heavily by Camilia Cuevas "Glitchtale" and TC-96's "Endertale". Undertale has so many wonderful fanfictions out there, so I decided to take a shot at writing my own (even though it will probably never even get close to the greats out there). I have a beginning and ending in mind, but I'm still making lots of this story up as I go along. We'll just have to wait and see were it goes. Hopefully, I won't get stuck like some of my others stories.

Please enjoy, and as always, any feedback is welcome and appreciated!

Prologue: A Perfect Ending

Frisk jerked up in his bed. He gasped for air and clutched his chest. Sweat poured from his brow as he frantically looked around. The dark outlines of the bedroom furniture surrounded them. He turned and saw his brothers sound asleep on the other bed. Chara snuggled up to Asriel and held him like a teddy bear, while Asriel buried his face into the boy's neck. Frisk's anxiety faded at the endearing display of affection. He caught his breath and let out a sigh of relief.

"Just a dream," Frisk whispered as he wiped his brow.

Unable to fall back to sleep, Frisk flew his covers off and stood up from the bed. He walked out of the room and made his way through the dark hallways of his home. He reached the kitchen and turned on the light. Frisk took a seat at the counter and laid his on his arms. He took a deep breath through his nose and closed his eyes.

Three months had passed since monster kind was freed. Asgore busied himself making negotiations with the human government. Undyne, Toriel, and Alphys taught at the local High School. Papyrus helped trim the hedges for the school with Asgore as the new head of the Royal Guard. Sans did his thing and loafed around. Mettaton started his own show. And with the help of a mysterious friend, Frisk brought back the Dreemurr children. They lived together with their Mom. All of them attended the school she taught at. This was it. He couldn't get a more perfect ending than this. After countless attempts, he'd finally achieved the impossible. The Dreemurr children were alive.

Frisk opened his eyes and looked up at the ceiling. No matter how hard he tried, that feeling of terrible dread and foreboding never ceased for good. Frisk couldn't quite put it into words. Something about all of this didn't seem quite right. The saying "too good to be true" must apply to situations like this, he thought. An old sensation, a haunting chill that crawled up his back, like a winter breeze that blew against his exposed, naked skin. Others might call it a superstition, no doubt. A paranoia perhaps. Frisk thought about telling his friends, but he didn't want to stir up unnecessary fear. They had gone through enough, especially his brothers. If his fears got worse, he would speak up, but for now he let them rest. He could endure this on his own. He'd gone through worse.

A strange, eerie sound like a distorted bell chime shattered his chain of thought. Frisk turned around in his chair. A dark void slowly manifested in front of him like a swirling black hole. Frisk smiled as his mysterious friend emerged from the portal with a grin of his own. He stepped through, his figure more solid than before, and the portal closed in on itself.

"Dr. Gaster," Frisk said the man's name as he sat down on the chair next to him, "I wasn't expecting to see you again so soon. You're…uh…looking a lot better."

"Thank you, child," Gaster rubbed his own cheek, "Yes, my body is starting to accumulate again, slowly but surely."

It was on his fifty-eight reset that Frisk finally encountered Gaster. At first, he could only speak in hands, but over time with each reset, he recovered his speech. Neither of them fully understood why he managed to come back, but Gaster's hypothesized that it had something to do with Frisk's determination. After each reset, Frisk came back a bit stronger, and Gaster fed off his determination. While enemies at first, overtime they became good friends, and Gaster helped Frisk bring the Dreemurrs back (but that is a story for another time). Sans, Chara, and Asriel were the only other one who knew about his existence.

"Can I get you something to drink?" Frisk offered, "I'm sorry, I wasn't expecting company."

"That's is quite alright," Gaster put a hand up to him, "And I don't think I'm quite ready to eat or drink yet. We should wait on that."

"Oh, of course," Frisk let out a nervous laugh and scratched the back of his head, "I guess I just assumed."

They sat in awkward silence for a few seconds until Frisk spoke up,

"So, why are you here?"

"I think you already know the answer to that."

Frisk's smile broke. He swallowed deeply and looked away.

"You could sense my fear, huh?"

"One more evidence that it is your Determination fueling me," the man looked at him with a clerical look. It was one of the few times Gaster actually looked and sounded like a scientist, "But I did not come to discuss theory. I am here to solve a problem."

"I don't know if there is a problem," Frisk sighed and rested his chin on the counter, "I have nothing to be afraid of."

"Is that why you won't tell anyone else?"

"What am I supposed to say?" Frisk shrugged, "It'll just sound like I'm paranoid."

Gaster frowned at him.

"Frisk, are you forgetting your role in all this?" Gaster began, "Like it or not, you aren't normal. You're Determination is beyond measure. You have the power to save and reset the timeline. If you're feeling afraid, we should all be afraid."

"The whole universe doesn't have to revolve around me!" Frisk shouted, and then they quieted their voice, "Surely I'm not the only 'special' one. Flowey had that power as well."

"Yes, but right now, as far as we know, you possess more Determination than anyone else," Gaster gave him a very serious look, "I have some theories as to what might be happening, but I need your help. Have you ever felt this way before? Can you think of any other instances where this feeling of dread arose?"

Frisk thought about it for a moment, and his face turned pale. He swallowed deeply.

"Right before we met each other, I started getting it. And before I met Chara in person for the first time, it happened then. In both timelines, the feeling was there."

"And what Flowey?"

"No, not for him. In fact, I was caught completely off guard the first time we met."

"I see," Gaster put a hand underneath his chin, "Chara and I did share a similar existence, I suppose. Unlike Flowey, we were trapped in some sort of upside-down reality somewhat connected to this one, a "spiritual" realm for lack of a scientific term. Void is probably more accurate. Soulless, but somehow there, nonetheless."

"So, what you're saying is that it's possible this feeling I'm getting is coming from something within that void, and it is beginning to manifest?" Frisk asked, feeling another chill run up his spine.

"It's possible, be we shouldn't jump to conclusions," Gaster explained, "This realm is unlike our own in every way. We cannot measure it."

"But weren't you just there?" Frisk asked, "Isn't that where you live?"

"Not exactly," Gaster shook his head, "That is more of a reflection of this world, a place created of my own mind where I can more easily navigate and exist. But it is dangerously closer to the void. Think of it more as a gateway, but don't take the image as reality."

"I can sort of understand that," Frisk's baffled expression betrayed his words, "But, what exactly does this mean?"

Gaster thought for a moment and spoke.

"I will see if I can find anything. Make sure to tell Sans about this. Maybe he has something to say about it. As for your brothers, either way. Whatever makes you more comfortable."

"I'll be on the lookout for anything suspicious," Frisk tightened his fists and looked down at the counter, "I don't want to risk losing this timeline, not after everything we've worked towards."

"Then let that motivate you to press on," Gaster smiled at him, and his form began fading, "It seems my time is already running out. I must go now. Take care of yourself, old friend, and good luck."

The portal reopened and absorbed the man. Frisk's anxiety returned with his absence. Gaster's presence always made everything feel much more safe and secure, almost like a guardian angel of sorts. One that would never lie, but always make the truth look as bright as possible, even if it hurt a little. With him gone, Frisk was left alone to his thoughts again, but not for long.

"Frisk?" a familiar voice called out to him.

He jumped a little and immediately turned around. Chara stood at the hall entry with a hand on the rim. Asriel was behind him.

"Who were you talking to?" Chara walked into the kitchen, dragging a half-asleep Asriel with him.

"Gaster dropped by for a visit," Frisk smiled.

"It's passed midnight," Asriel yawned and rubbed his eye, "Why are you guys up? And why did you bring me too?"

"I'm sorry, I didn't mean to wake you guys up. I just had a hard time sleeping."

"Again?" Chara frowned at him and sat up on the counter, "That's like the seventh night in a row now."

Asriel took a seat on the chair next to Frisk and laid his head down on the counter with his arms tucked underneath.

"If it was Gaster, it must have been pretty important," Asriel mumbled.

"I wish you would've gotten us," Chara gave a pouty face and crossed his arms, "You guys are always leaving us out of the loop."

"I didn't even know he was coming," Frisk explained, "He showed up on his own."

"What did he want to talk about?" Asriel lifted his head, a bit more awake now.

"My sleeping problems."

Both Asriel and Chara looked at Frisk curiously.

"Well, what about them?" Chara asked impatiently.

"We're just trying to figure out the problem." Frisk shrugged, "He wants to make sure it's not anything serious."

"Like what?" Chara pressed him.

"I don't know, that's what he's trying to figure out," Frisk gave them a reassuring Sans smile, showing all his teeth, "Look, don't worry about it, ok? If anything happens, we can all look out for each other. I'm sure of it."

Chara glared at Frisk with his arms crossed. Frisk's smile disappeared.

"What's with that look?" he asked, "Do you not trust me?"

"I'm a little questionable of your honesty," Chara continued, "How do I know you're not planning on doing something on your own again? That's how you've done everything else."

"Hey c'mon, that's not fair!" Frisk snapped back, "I never asked for these powers, ok?"

"We're just concerned Frisk," Asriel put a hand on his shoulder, "Chara and I know firsthand what happens when you try to do everything on your own."

"Exactly, and we don't want the same thing to happen to you," Chara jumped off the counter, "Not just for your sake, but everyone else's."

"Well, that's why we're brothers, aren't we?" Frisk grinned and got them both in a head lock.

Frisk laughed as they struggled to break free. Their wrestling was brought to abrupt end, however, when they saw their mother standing in the hall entry with her arms crossed. Asriel and Frisk's face's turned bright red, and Chara rolled his eyes.

"Great, way to go hero," he mumbled.

Frisk let go of them, and both he and Asriel let out nervous laughs.

"Hi Mom!" Asriel shifted uncomfortably, holding his hands, "Uh, we were just, um…"

"I saw a cockroach!" Frisk rose his hand with a desperate face, "Yeah, I saw a cockroach on the floor and…eh…"

Chara looked at them both with a raised eyebrow and huffed. Toriel let out a deep sigh and closed her eyes.

"Well, I suppose I should just be grateful tomorrow's a Saturday," she opened her eyes, "Frisk, honey, are you still having nightmares?"

"It's not a big deal," Frisk waved his hands, "Really Mom, I'm fine.

"He woke us up," Chara pointed a thumb at Asriel.

"You mean he woke you up, then you woke me up for some reason," Asriel glowered at him.

"Well, it doesn't matter who woke who up," Toriel walked into the room with a bright smile, "How about I make us all some hot chocolate?"

Chara mood changed instantly and he gasped.

"Oh, yes please!" he raised his hand.

"Me too!" Asriel jumped in.

"Sure, I'll take some," Frisk smiled somewhat halfheartedly.

Toriel began boiling hot milk on the stovetop, while Chara and Asriel pulled out the coco mixer, marshmallows, and coffee mugs. Chara pushed Asriel to rip the marshmallow bag open with his teeth, resulting in marshmallows flying everywhere. Chara scolded him, and Asriel argued that it was his idea before Toriel demanded they get along and clean up their mess, or else neither of them would get any hot chocolate. Frisk sat down at the counter and watched them with a soft grin. They prepared their cups and sat down at the counter together, drinking and talking. Frisk remained quiet for most of the time and listened to everyone talk. Despite everything that had happened, despite all the trauma and heartbreak, things were coming together. He clutched his chest again.

"This is what I'm fighting for," Frisk thought to himself, "No matter what happens, I will do whatever's necessary to protect them all, even if it means sacrificing my very soul."

Everyone finished their beverages and headed to bed. After that night, Frisk's sleeping improved.