A few days passed, and Frisk and Gaster's friendship developed. They talked about several topics; the examples would be the human world, as Gaster didn't know much about humans, Sans and Papyrus, their experiences and likes and dislikes. It already looked like they were good old friends. Gaster was feeling way happier after being friends with Frisk. He finally had someone to talk to. The child appeared to be happy, too. They liked being friends with him and did their best to make him feel better about himself, after everything he had done.
Although Frisk usually talked to Gaster when they weren't around anyone, their friends had already seen the child talking to the "invisible man" in a few occasions. Toriel sometimes asked Frisk about Gaster, but, of course, being oblivious to the thought of him being real.
"Did you play with Gaster today?" Toriel asked. Frisk just realized that she probably didn't imagine Gaster being an adult... usually the questions involved child things (which, of course, did not imply that Gaster wouldn't play with a child, as he was a father, after all).
"Yes, we had a lot of fun while, um... watching cartoons."
Sans and Papyrus didn't know about that until Toriel revealed them that their friend was sitting on the couch while Frisk watched the TV one day.
"FRIEND? WHAT FRIEND?" Papyrus asked.
"It's their friend Gaster." She said. "He's sitting next to them, so I wanted to make sure you won't sit on him."
"OH... OH, I GET IT! OKAY, I WON'T SIT ON HIM!" Papyrus winked at Toriel.
Toriel sighed, relieved. At least Papyrus understood what she meant. With that, she went back to the kitchen. Frisk glanced at Sans and... they noticed something strange about his expression after Toriel said... that name. Frisk didn't say anything to Gaster, who was distracted by the TV at the moment. Frisk wondered if Sans remembered Gaster... He suddenly wasn't smiling anymore, like he usually did. Papyrus noticed that and touched his shoulder, with a concerned face.
"SANS, ARE YOU ALRIGHT?" He asked.
"i... i'm fine, pap. i just... need to go to the bathroom."
Sans left the living room, going upstairs. Papyrus sighed.
"OH BOY... HERE WE GO WITH SANS NOT TELLING ME ANYTHING." He murmured to himself, but Frisk was able to hear that.
The child looked at Papyrus sadly. The skeleton looked back and then he went back to his cheerful personality.
"ANYWAY, WHAT ARE YOU AND YOUR FRIEND WATCHING?" He asked.
Papyrus sat on the other corner of the couch, aware of Gaster's presence on the middle of it. With that, the trio watched TV for a long time on that day.
Meanwhile, at school, some of Frisk's friends had seen them talking to Gaster (who, of course, could not be seen). Some of them thought it was weird but didn't say anything about it, while others didn't care at all.
In general, nobody judged Frisk for having an "imaginary friend". They all went along with it.
Papyrus just finished cooking some spaghetti for dinner.
"DINNER IS READY!" He said.
Toriel could see the spaghetti from where she stood. She was able to smell it.
"Oh, I already like the smell." She said. "I bet the taste is even better."
Papyrus put the spaghetti on four plates, giving two of them to Sans and Toriel. Sans started to chuckle.
"how do you say, papyrus?" He asked.
"WHAT?"
"you know... bone appetit?"
Toriel giggled, while Papyrus groaned loudly, facepalming with both hands.
"AGHHHH!" He yelled.
Meanwhile, Toriel took one bite from the spaghetti.
"Mmm, Papyrus, this is really good!" She said. "I see you have been improving even more lately."
Suddenly, Papyrus completely forgot about Sans's terrible pun and blushed lightly at Toriel's compliment on his cooking.
"REALLY? AWW, THANK YOU, LADY ASGORE!" Papyrus said.
Toriel rolled her eyes. "Toriel."
"WELL THEN... THANK YOU, LADY TORIEL."
Toriel shook her head in disapproval, but she couldn't hide the smile. She continued to eat the spaghetti. The skeletons started eating, too. Papyrus glanced at the empty chair where Frisk was supposed to sit. Even after he yelled that the dinner was ready, Frisk didn't come.
"WHERE'S FRISK?" Papyrus asked.
"They are in their bedroom, I think." Toriel answered. "They started being alone in there for a while... they're probably talking to Gaster, their imaginary friend."
Sans suddenly frowned. Papyrus noticed that again, but he didn't say anything. He knew that Sans wouldn't tell him what was wrong. Toriel, however, asked him anyway, as she didn't really know how mysterious Sans used to be.
"Are you alright, Sans?"
"i'm okay."
NO, YOU AREN'T. Papyrus thought.
Toriel stood up and said: "Well then... I better call Frisk, or else their food will cool."
She left Sans and Papyrus in the kitchen and headed to Frisk's bedroom. Before knocking on the door, however, she heard Frisk talking to their imaginary friend.
"I can't believe it! They really were terrible when they were kids."
Gaster was talking about Sans and Papyrus to Frisk, when they were only children. According to his memories, the skeleton brothers haven't changed anything, except for the fact that Papyrus wasn't so confident about himself. When they were little, they still teased each other, while still caring a lot about each other... actually, they were way worse.
"They stayed almost the same, honestly." Frisk said. "They still tease each other."
OH, THESE BOYS... Gaster laughed. THEY GAVE ME A LOT OF WORK...
Frisk heard a knock on the door. Then it was opened by Toriel.
"Frisk? I don't think you have heard Papyrus say that dinner was ready, so..." Toriel said.
"Oh! Sorry, I didn't hear that. I'm coming."
Frisk stood up and gave a fast smile to Gaster before following Toriel to the kitchen.
"DIDN'T YOU HEAR ME CALL YOU, FRISK?" Papyrus asked.
"No, sorry about that."
"WELL, IT'S OKAY! AT LEAST YOUR SPAGHETTI IS STILL WARM!"
Frisk sat on the empty chair. They ate the spaghetti, which was quite delicious.
They're probably talking to Gaster, their imaginary friend.
Gaster.
That name gave Sans a bad memory. A memory that he hadn't remembered in a while.
Everytime he heard that name, it came back to his mind.
That one memory...
"Dr. W. D. Gaster, y-your father... he suffered an accident with one of his experiments and... I... I am sorry."
Sans was a little kid again. A monster - another scientist - visited his house to let him know about the tragic accident that his father had suffered. The little skeleton looked at the man in complete disbelief. Sans understood what he meant.
"w-what...?" He said, quietly.
He felt like he was punched in the stomach, despite not having one. His dad had promised him he would be back home. He promised that he would take his sons outside to play in the snow. He promised they would build a snowman and make snowballs to throw at each other. He promised that they would finally spend time together.
He promised.
"S-SANS?"
Sans saw Papyrus behind him. His little brother was really worried. Sans really hoped that he hadn't heard what happened to his father.
"WHAT... W-WHAT HAPPENED TO DADDY?" He asked.
"papyrus..."
Papyrus approached Sans and the scientist.
"Your father... he... he suffered an accident." The adult said.
"BUT... H-HE WILL BE OKAY, RIGHT?"
Sans's heart broke completely. His brother was so innocent... The scientist sighed sadly, shaking his head.
"I am deeply sorry." He said.
Papyrus's eyes widened and they formed tears.
"NO... NO..."
Sans hugged his brother tightly. Papyrus sobbed on his shoulder, saying "no!" multiple times. Sans cried quietly.
"i can't believe he's gone..." Sans whispered.
Sans shook his head, trying to take that off his mind. That memory still haunted him; he didn't get over his father's death. He tried to stay cool. He was having dinner with his friends and his brother and he really didn't want to be seen crying. He absolutely hated to talk about that topic.
He stayed quiet the whole time. Nobody really said anything about Sans being silent. He took a long time to finish eating while everyone else already finished their food.
Toriel was washing the plates when Sans finally finished his dinner. He then put his plate on the sink.
"i can help you with the dishes." He said.
"Thank you, but don't worry about that." Toriel gave him a worried smile.
He could see that she did notice that he wasn't feeling well, but she didn't ask anything. Sans appreciated that and smiled in return, then leaving the kitchen.
Sans told Papyrus he would tell him a story. He was very excited, already on his bed, waiting for his big brother. As soon as Sans arrived, Papyrus felt his excitement grow more.
"STORY TIME!" He said.
Sans gave him a weak smile. Papyrus quickly lost his joy as he noticed that Sans wasn't as happy that day as when he was going to tell his brother a story.
"SANS... SERIOUSLY, WHAT HAPPENED?" Papyrus stood up to sit on his bed, while Sans simply fell on his bed, groaning quietly.
"SANS."
"bro, i'm just tired."
"EVEN IF YOU ARE TIRED, YOU ALWAYS TELL ME A STORY! I KNOW THERE'S SOMETHING BOTHERING YOU. I NOTICED THAT EARLIER!"
Sans stayed silent. Papyrus stared at him and sighed deeply.
"SANS, WHY WON'T YOU TELL ME ANYTHING?" Papyrus asked. "YOU ARE ALWAYS HIDING THINGS... I AM YOUR BROTHER, I WANT TO HELP YOU!"
Sans sighed again. "it's... it's stupid."
"IT'S NOT STUPID IF IT MATTERS."
Sans finally had the gut to look at his brother. Papyrus went to his messy bed, sitting on it. Sans sat on it, too, to give him space.
"YOU CAN TELL ME, BROTHER." Papyrus said.
"i know, it's just... i don't really like to talk about it. but... okay, i'll tell you."
Sans turned his gaze to the floor, seeming ashamed.
"it's... it's all because of... frisk's new... friend." He admitted. "i mean, when toriel said his name, i... i had that terrible memory again."
Papyrus knew what he meant. The human's new imaginary friend was called Gaster. He had remembered his father when he heard the name, but he hadn't felt that bothered.
"i suddenly... turned back into a kid and... i just... remembered that guy telling me about... the accident." Sans continued. "ugh... everytime i hear that name this memory pops in my mind and i feel really..."
Papyrus felt bad for him. Sans still didn't get over his father's death, while he, at least, knew how to deal with it. Sans didn't like to remember that terrible day, and he didn't react well about it.
"OH, SANS..." Papyrus said.
Sans sighed. "why does frisk's friend have to be called... gaster?"
"SANS, YOU KNOW THAT CHILDREN CAN INVENT ANY NAME POSSIBLE FOR THEIR IMAGINARY FRIENDS."
"i know but... why... gaster?"
Papyrus gave him a hug. Sans didn't return it right away. They didn't say anything for a long time.
"I MISS HIM..." Papyrus finally said. "I KNOW HOW IT FEELS."
Sans sighed in response. He tightened the hug a little.
"i miss him so much, pap..." He admitted.
"ME TOO... BUT THERE'S NOTHING WE CAN DO ABOUT THAT, SANS. WE NEED TO MOVE ON."
He tried so hard to move on. He really did. But that memory would always be there, waiting for its next appearence. It would always haunt him. Sans, however, didn't want to talk about that anymore. He was deeply bothered about it. He let go of Papyrus.
"thanks, bro." He said. "i"m feeling better now..."
Papyrus smiled, being oblivious of the lie his brother told him. "YOU CAN ALWAYS COUNT ON ME, SANS."
"i know."
"THEN DON'T BE AFRAID OF TALKING TO ME ABOUT THINGS THAT BOTHER YOU, OKAY?"
Sans nodded in response.
"WELL, YOU BETTER GET SOME SLEEP... GOOD NIGHT." Papyrus said.
The taller skeleton went to his bed. Sans wouldn't let his little brother sleep without a story! He would do it, no matter how tired he was.
"hey pap?"
"YES?"
Sans gave him a happier smile. "wanna hear a story?"
Papyrus's face quickly lightened up, nodding.
"get comfy, bro." Sans said.