Another Undertale fic! I've been obsessing with this game, sorry ;v;

I wanted to note here that this fic is not related to I am here. And, like always, I apologize for any mistakes in the writing.

Still, hope you enjoy it! :)

Being stuck and alone in the Void was quite painful.

W. D. Gaster sighed while he fluctuated in the darkness of the Void, a dark, empty and cold dimension. He had been stuck in there since that terrible accident with one of his greatest experiments. While he was stuck, however, he at least could see what was happening in the real world. Nobody even noticed he was there, though; sometimes he even tried to talk to someone, but he was ignored. He even stopped doing that, after realizing how useless it was to call for help.

After he heard that the monsters were finally free, he lost his hope completely. He had always wanted to go to the surface, like any other monster. Even though he could visit the real world, he wouldn't be able to breathe the fresh air from the surface. Even worse, he wouldn't be able to cherish freedom next to his sons... actually, he was, but Sans and Papyrus wouldn't even notice him.

Gaster sighed sadly. It had been such a long time since he left reality. He wondered if Sans and Papyrus ever thought of him. Probably not. They were only kids when the accident occured. He wouldn't be surprised if they didn't remember him.

He stared at the darkness. He would be lonely for the rest of his life. He kind of deserved it, though. He wasn't a great father and he failed at giving monsters the freedom they all deserved. He could have destroyed the barrier years ago... but he failed.

He only wanted to make things right.

He wanted to be with his sons.

He wanted to go home.

Gaster cried. His tears fluctuated in the low gravity of the Void. He called for help, even though he knew how useless it was.

SOMEBODY...

PLEASE...

... I WANT TO GO HOME.

It was a beautiful day outside. Birds were singing, flowers were blooming. On days like these, Frisk enjoyed to sit on the grass, while watching the sunset. After spending a lot of time playing with other kids, they liked to have some alone time, aside from loving the sunset, specially with the beautiful landscape of the surface. Sometimes, Frisk watched the sun going down with Toriel, but she was busy at that moment. She had to do some school-related stuff. After that, she would bake a pie.

Frisk sighed happily, remembering the good life they had, after leaving the Underground. They were living with Toriel, Sans and Papyrus. Monsters were having a great life in the human world. Surprisingly – and thankfully -, humans were being receptive. Well, not all of them, though. Still, monsters were slowly getting accepted and were gaining their space.

The small child already planned what they were going to do at night. It was finally Friday; they could stay up until late. They thought of watching Mettaton's TV show and then cartoons with Sans and Papyrus. They could imagine the trio having fun while eating butterstotch pie. They could tell that it was going to be a fun night.

When the sun was almost disappearing, Frisk was able to see the shining stars. The human sighed again. The world might not be perfect, but it was a wonderful one. Then, the child heard Toriel call their name in the distance, since she already knew they would be watching the sunset. She worried that Frisk could get lost in the forest near their home and cold, as the city's weather wasn't that hot, specially on that day. Frisk didn't protest. They didn't really like to wander around the woods at night, even if they liked to see the stars.

Frisk ran to the house, ready to give Toriel a hug. As they approached, they saw their Goat Mom (they loved calling her like that; she was very fond of that nickname) waiting for them, holding her own hands, which were covered by oven gloves. She gave Frisk a big smile when they reached her.

After they hugged, Frisk entered the house. Toriel closed the door. The child's stomach rumbled when they smelled the butterstotch pie.

"I see you are hungry." Toriel said. "You better eat something light. It will take a while to be ready."

Gaster gave up on calling for help. Why was he even doing that? Nobody could listen to him, no matter how loud he screamed. He sighed. He stopped crying, after realizing that it was useless.

CRYING WILL NOT BRING ME BACK HOME. He told himself, trying to stay calm.

He tried to stay positive. At least he was able to know what was happening in the real world, right? Because if he didn't, he would be suffering even more. And thank goodness he was able to see Sans and Papyrus. Gaster smiled sadly when he imagined what they were probably doing at the moment.

He was very proud of them, despite Sans being lazy... His elder child did a great job taking care of Papyrus when he was younger – he was a great brother. Gaster would say the same for Papyrus.

Gaster promised to himself that he would always be there for his sons, even after he disappeared.

Then... why the hell was he not doing that at the moment?

He groaned. He was so focused on sadness that he didn't even check Sans and Papyrus after going to the surface. He breathed heavily. He decided to stop focusing on himself to keep his promise. He wouldn't break it. Not again.

Finally, he left the darkness and emptiness of the Void. He knew they wouldn't stay in the Underground after the destruction of the barrier, though he didn't know where they were. Thus, he ended up arriving somewhere close to Mount Ebott. The sky was black with several stars iluminating it. Gaster looked around. He found several houses and buildings in the distance. He... he couldn't really walk, as he didn't exactly exist. He had to fluctuate in order to move.

He fluctuated around... he only found grass, trees, some small animals... A few meters away from there, he found a nice, tidy and cute house. Curious, he approached it. He found several flowers standing in the garden, as well as hearing some voices coming from the house...

... they were... familiar?

Gaster floated to the window's direction. He gasped when he recognized the voices and the ones inside it. There they were: Sans and Papyrus. They were eating pie with a female goat and a little human child. Gaster could feel a warming feeling inside his heart after seeing how much fun his sons were having. The goat and the child seemed very nice. Actually, Gaster could tell he had seen the woman before. Her voice was familiar, too, but his memory failed. Same for the human... In any case, he just admired seeing his sons happy. The pie appeared to be delicious... too bad Gaster couldn't even eat (he didn't need to, for somewhat reason; after staying trapped in the Void, he didn't need to sleep nor eat).

He paid attention to the conversation.

"SO..." Papyrus said, looking at the human. "HOW WAS YOUR DAY?"

The child answered, in an adorable voice:

"I played with my friends after school. We played the whole afternoon! We had a lot of fun!"

"That's great, my child." The woman said.

They were all happy, laughing with each other. Sans said some bad puns, making Papyrus annoyed, yet smile at the terrible joke. Gaster chuckled. Sans never changed... he made bad puns since he was just a little kid. Papyrus secretly loved them.

Gaster sighed. He was kind of happy, which was a strange feeling, specially when he spent most of his time in the Void, unhappy and lonely. Watching Sans and Papyrus happy was way better...

Frisk was almost sleeping. It wasn't even midnight... They frowned a bit when they looked at the clock. They wanted to stay awake. Their favorite cartoons were about to air. Meanwhile, Mettaton's show was still on TV. It wasn't a new episode, but they liked watching some of them more than once.

Frisk glanced at Sans. He already fell asleep... they chuckled. Papyrus was still awake. He looked at Sans, too, and he rolled his eyes.

"TOO LAZY TO SEE METTATON... HMPF." Papyrus whispered, making Frisk laugh a bit louder. It didn't wake Sans up, though.

Papyrus noticed how tired Frisk looked.

"FRISK, YOU SHOULD GO TO BED." He said.

Frisk whined. "Ugh, I don't want to..."

"BUT YOU ARE TIRED! YOU NEED TO REST! AFTER ALL, YOU WAKE UP EARLY EVERY DAY BECAUSE OF SCHOOL."

Frisk couldn't deny that. They had that routine of waking up early... Convinced, they stood up.

"I'M GOING TO BED, TOO. I GOTTA CARRY SANS TO HIS BED..." Papyrus said, glancing at Sans, unimpressed.

Frisk gave a tired smile. "Good night."

"HAVE A GOOD NIGHT, FRISK!" Papyrus smiled back.

The little child walked upstairs. They could hear Papyrus talking to Sans.

"ALRIGHT, SANS, LET'S GO TO BED."

Sans groaned. "i like it here..."

"YES, BUT WHAT IS THE PURPOSE OF YOUR BED IF YOU DON'T SLEEP ON IT?"

With that, Sans stayed silent. Papyrus turned off the television and carried Sans to their room (they shared one). Frisk went to Toriel's bedroom to give her good night. The door was open and she was still awake, reading a book.

"Hey, mom? I'll go to bed now." Frisk said.

Toriel glanced at the child, smiling.

"Alright, good night, dear." She said, giving Frisk a good night kiss when they reached her.

"Night, mom."

Frisk left Toriel's room and entered their own. They put on their pajamas to go to bed.

Gaster had a sad smile on his face while he observed his sons sleeping peacefully. He tried to touch them... that didn't work, obviously.

GOOD NIGHT, MY BOYS... He said, even though he knew that they wouldn't listen.

He felt his eyes getting wet. It hurted. It hurted to not be there for his sons, when they didn't even know he was next to them. He didn't even... exist. And nobody remembered him. He promised he wouldn't leave his sons, but... how was he going to help them if he wasn't even there?

Gaster would be alone forever. Nobody would ever speak to him. There was no reason for him to be there anymore. Sans and Papyrus were doing well without him. They didn't need him. They weren't kids anymore. He was... he was wasting his time.

I... I DON'T WANT TO BREAK MY PROMISE. He said to himself. BUT WHAT CAN I DO FOR YOU... IF I DON'T EVEN EXIST?

Gaster breathed heavily. Tears wouldn't stop falling. He started sobbing and left Sans and Papyrus's bedroom. He had to let them go. He was lost in another dimension, there was nothing he could do for them.

The lonely scientist sat on the floor of the corridor (somehow, he didn't pass through the floor) and cried. He felt his heart ache.

Frisk took a while to get prepared. Finally, when they lied on the bed, they closed their eyes. They were about to sleep when they heard some strange noises...

They sounded like... sobbing.

Someone was crying.

Concerned, Frisk immediately opened their eyes. Who could be crying? They quickly stood up and walked to their room's door. The sobbing was coming from the corridor. They opened the door. The other rooms' doors were closed. The child looked around, only to find someone... someone they had never seen before. The stranger was bald, had white skin. Their face was covered by their hands, which had holes. They wore a black overcoat. They sat on the floor, crying.

How did they get in there? How did they enter the house without making any noise? Frisk's eyes widened. Before calling Toriel for help, they wanted to know who was that stranger, and why were they crying. The child slowly approached them.

"H-Hello?" Frisk whispered.

The stranger didn't seem to notice them. They just kept crying.

"Mister...?" Frisk tried again. "A-Are you... okay?"

Suddenly, the unknown... person stopped sobbing. They anxiously looked at the child. They gasped, distancing themself. Frisk looked at them, confused, but with some concern.

WHAT THE... A-ARE YOU... TALKING TO... ME? The stranger asked. They sounded to be a man.

Frisk nodded, confused, but trying to be patient before screaming for help. The man didn't seem to be dangerous, actually. Apparently, he was just a very sad man who needed some comfort.

"Who... who are you?" Frisk whispered.

The man took a while to answer. He looked very surprised after Frisk confirmed that they were talking to him.

I... I AM... W. D. GASTER. He said, sounding nervous. He sniffled.

That was extremely unbelievable.

That child was talking to him. They could listen to him. They could see him. How was that even possible? Nobody else noticed Gaster's presence. That didn't make any sense!

"Why are you crying, mister Gaster?" The child asked, keeping their voice down. "And... and how did you get here?"

Gaster sniffled again. How would they explain the whole situation he had been through? How would he explain that he was stuck in another dimension because of an accident? It would be too much for a child.

But... they were genuinely concerned about him. Nobody knew how it was to be stuck in the Void. He had never opened up about it because nobody listened to him. He didn't want to throw the opportunity of talking to someone away.

He sighed. IT... IT IS A LONG STORY, CHILD...

The little one approached him more, curious, yet somehow scared. Well, who wouldn't be scared of an unknown man who just showed up in their house?

Gaster had... a strange appearence. He had two scars on his face. His eyes were big and had white pupils... Suddenly, Frisk thought of Sans. Both had white pupils. Well, that was just a coincidence.

The child waited for him to speak. He seemed anxious to tell them.

LOOK... He began. IT IS VERY COMPLICATED, IT IS FINE IF YOU DO NOT UNDERSTAND, BUT...

WELL, YOU SEE... I WAS A SCIENTIST. THE ROYAL SCIENTIST OF THE UNDERGROUND. MANY YEARS AGO, I CREATED A MACHINE THAT WOULD FREE THE MONSTERS. HOWEVER... IT WENT ALL WRONG. THE MACHINE WAS DANGEROUSLY UNSTABLE AND IT... IT ABSORBED ME. THEN IT BROKE. HOWEVER, FOR SOME REASON, I HAVE SURVIVED...

... BUT I... I WAS SENT TO ANOTHER... DIMENSION, THE VOID. A DARK, EMPTY DIMENSION. SINCE THEN, I HAVE BEEN STUCK IN THERE. I CAN STILL SEE WHAT HAPPENS IN THE REAL WORLD, BUT... NOBODY CAN SEE ME, OR LISTEN TO ME. I HAVE BEEN FEELING QUITE LONELY.

Frisk wasn't confused at all. They had seen some weird stuff in the Underground, after all... It did surprise them, though, that he was still alive, somehow. Besides, nobody else even noticed his presence.

I... I JUST CAME TO YOUR HOUSE TO... TO SEE MY SONS.

Sons? Was he talking about...

"You mean... Sans and P-Papyrus?" Frisk asked.

Gaster nodded sadly. THAT IS RIGHT.

Frisk's eyes widened. They had a father? It sort of made sense, considering that they were brothers, but... none of them have ever mentioned Gaster before. Not as Frisk remembered.

BUT... THEY DON'T EVEN KNOW I EXIST... More tears fell from his eyes. THEY DON'T KNOW I'M HERE. NOBODY DOES.

Frisk looked at him with a sad face. He was just a lonely, lost man, who wanted someone to talk to, who wanted to be there for his sons.

"I... I'm sorry." That's all Frisk could say at the moment. They really were sorry.

DO NOT WORRY, CHILD... W-WELL, I BETTER LEAVE NOW. He said, standing up. I DO NOT BELONG TO THIS WORLD ANYMORE.

Frisk didn't want him to leave. He was really sad and lonely. They didn't want him to suffer like that. The scientist was ready to leave when Frisk blocked the way, even though he could just pass through them.

"D-Don't go, mister Gaster!" Frisk said, trying to keep their voice down. "I don't want you to be alone."

I... I WILL BE ALRIGHT, HUMAN.

"No, you won't... You will be even more lonely. I don't want that for you."

Gaster looked away. HUMAN...

"Stay. I want to help you."

YOU CANNOT HELP ME, CHILD...

"I... I can be your friend, mister Gaster."

He looked at them with surprise. WHAT?

"Isn't that what you want? I mean, you said you were lonely and nobody knew you existed. But I know. I'm here, talking to you. I... I don't want you to leave. I don't want you to suffer."

That child... they were so sweet. They were concerned about him. They wanted him to stay.

HUMAN, I...

"Please... don't you want someone to talk to?"

Of course he did. All he wanted was someone who he could open up to. He was so lonely, he was neglected by everybody. He... he only wanted a friend, someone to trust.

YES, BUT...

"I will be your friend, mister Gaster." The child said, with a sad smile on their face. "Please, don't go."

He sighed. He was... he was feeling better, actually. He didn't feel his heart aching that much anymore. The presence of the child was helping him a lot.

Somehow, he reminded of Sans and Papyrus, when they were only kids. He remembered when they wanted to cheer him up when he wasn't feeling well... Gaster had done the same thing: distance himself. Not in an aggressive way, but... it made their sons think that they were annoying him. That was the worst thing he could've ever done to them. He loved them so much... how dare he do that to people who cared so much about him?

He wouldn't make the same mistake. That child genuinely cared about him. They wanted to help him, just like what Sans and Papyrus would do for him. He sighed sadly. He managed to give them a smile. Remembering his mistakes was something really painful. He was about to cry again...

OKAY, I... I WILL STAY HERE, CHILD.

The human's smile lost a part of the sadness. They yawned, suddenly.

OH, YOU MUST BE VERY TIRED... YOU BETTER GO TO BED.

"Yeah, I will go to bed now... You can come with me to my bedroom, if you want."

The child opened their bedroom's door. They waited for him to come in. A little hesitated, he entered the room.

ARE YOU SURE YOU WANT ME HERE?

"Well, only if you want to." They said, giving a tired smile.

Gaster shrugged. The child laid on their bed, breathing deeply.

HAVE A GOOD NIGHT, HUMAN.

The child chuckled quietly before closing their eyes. "Good night... and, uh, my name is Frisk, by the way."

He smiled at them. Frisk quickly fell asleep. They were very tired... Gaster felt a bit clumsy by staying in that child's bedroom. They didn't even know him that much, yet they were willing to help him, to be his... friend. What a friendly and sweet child. It reminded him of Papyrus... The younger skeleton loved to make friends, and was also willing to helping others.

Gaster smiled sadly while looking at Frisk. Then he sighed. He wasn't sure what he could do. All he did was lay on the floor. He didn't do anything but that. At least he had some company... He was glad that Frisk was there, knowing that he existed.

Gaster closed his eyes.

This chapter turned out to be longer than I thought... sorry if it was slow, but I liked to focus on Gaster's feelings and Frisk's new life with Toriel, Sans and Papyrus.

So... what did you think? I hope this wasn't hard for you to understand, though ;v;