Sans was really serious about helping Gaster with the DT experiments. Gaster had let Sans help with The Core before but the DT experiments were different, more dangerous, more stressful and Gaster was hesitant to let a seven year old get involved. He gave Sans access to videos and written research, and asked him to write theories and run simulations. Gaster tried to keep him away from the physical experiments but Sans snuck in anyway and he had began to convince Alphys to do the same.

Gaster didn't like having a seven year old and a twelve year old around DT but they were insistent and they were geniuses. Alphys needed more confidence and Sans needed to be more positive and hopeful but they knew what they were doing and they worked hard, harder than the adults sometimes. The only thing Gaster and Alphys's father could do was watch over their children and make sure they stayed safe.

They looked into all kinds of effects DT could have, all the powers that could be unlocked with it, more magical power, immortally, the ability to manipulate space, time travel, the list was endless and Gaster was hesitant to go through with any of the experiments, they were too dangerous. He didn't even have a test subject but Sans kept volunteering; arguing that he was made to be experimented on originally. Of course Gaster refused, he wasn't going to experiment on his own child. Besides Sans was too young to make that decision, he wasn't even old enough to drink, vote or have sex, there was no way he could consent to experimentation. Gaster kept a close watch on him after he insisted on it; he couldn't let Sans experiment on himself.

Gaster was stressed out, he worried about the barrier, he worried about Asgore, he worried about Sans and he still had Papyrus to look after. Papyrus was a very happy child, always laughing, unless Sans told a joke, and seemed to love being surrounded by people. Gaster found spending time with his youngest to be very relaxing despite the fact he was a more difficult child that Sans was; he couldn't get him to sleep, he always wanted to do something, he cried in the middle of the night but Gaster loved him. Papyrus's happy energy always lit up a room, everyone loved him and it seemed to be impossible for anyone to be sad in Papyrus's presence. Gaster was proud of both of his sons; his eldest was a genius and his youngest was a cute little ray of sunshine that was too pure for this world.

There were long nights, where Gaster was hunched over a desk, stressing and raging over his work. He'd throw things across the room, he'd smash things in frustration, he'd punch the wall in anger but he made sure his sons didn't see him like that. He did his best to be a good father and he spoilt his children, he gave them everything they wanted, within reason of course. Work drove him mad, he knew that without his boys he would have probably gone insane long ago.

Much like what he was doing with Sans, he also started a journal about Papyrus filling it with the same kind of things he did Sans's. He just happened to be filming when Papyrus first started walking. He was filming because Sans had given Papyrus a bowl of plain spaghetti when he was sitting on the floor in the living room, Papyrus was making a mess but Gaster didn't care it was cute so he filmed as the child waved fist fulls of pasta around.

Sans came into the room with freshly heated pasta sauce and a big smile on his face as he announced "come and spaghet it."

"NYEH!" Papyrus looked annoyed but instead of simply cringing and moving on like normal, he threw the spaghetti at Sans, hitting him right in the face. Sans stood there shocked still.

Gaster burst out laughing, the camera shacking as he tired to control himself. He couldn't believe he got that on film!

Feeling happy with the footage he went to turn off the camera but stopped when he heard Sans gasp and he looked up to see Papyrus standing on shaking legs. He zoomed in on the infant and focused the camera just in time to capture his child take a slow step forward, then another and another. Papyrus looked really proud of himself as he walked over to his spaghetti covered brother. Papyrus walked with a purpose and when he reached his brother he reached up to him with a grabby motion with both hands. Sans bent down and picked up his brother.

"aww, papy! well done, you're so smart. did you want hugs from your big bro?"

Papyrus reached out to Sans's face and grabbed a noodle off of him and began eating, Sans looked a little disappointed but laughed anyway, "you just didn't want to waste the pasta?"

Gaster was in a fit of laughter, the whole thing was hilarious! "BOTH MY SONS WALKED FOR FOOD..."

"huh?"

"I'LL SHOW YOU THE VIDEO LATER."

Gaster took a long drag of a cigarette; he was so stressed and was getting nowhere with his research. He was smoking more and more and the nicotine patches and gum Asgore was buying him didn't work, he needed cigarettes and was smoking at least two packs a day. He knew it was bad, he didn't have lungs but it still wasn't healthy, he knew he should quit. He didn't want Sans or Papyrus to start the bad habit just because he did it but it was so hard then he was trying to work and all he could think about was getting his fix.

He'd never smoke in front of his children, however. Sans knew he did it, Papyrus was only a year and a half so he probably didn't understand what he was doing but he was just as smart as Sans was. He made sure that Sans knew smoking was a bad thing and he would do the same with Papyrus but it was something he worried about.

He lent against the wall outside of the lab one foot up and touching the wall as he took another long drag, then lent his head back hitting his skull hard on the wall, he didn't react to the pain just stayed there staring at the roof of the cave. He wanted out. He wanted to see the sky, not rock when he looked up, he wanted to feel the warmth of the sun not the warmth of the magma of Hotland. He felt trapped and claustrophobic. He wanted out of the Underground and he was still so far away from it and it was frustrating. He was angry at himself for not figuring it out yet. He wished he was better.

He finished the cigarette and flicked it away before he pulled out another, sticking it between his teeth and then pulled out his lighter. As he flicked the lighter on he heard the door open and Sans ran out, shouting, "DAD!"

Sans never ran, Sans never shouted, Sans never used uppercase; something must be wrong, very wrong. Gaster pocketed the lighter and cigarette and grabbed his son's arm, trying to fight the panic.

"SANS? WHAT'S WRONG? WHAT HAPPENED? ARE YOU HURT?"

"huh? what? i'm fine! you gotta come quick though."

"WHY? WHAT HAPPENED? PLEASE TELL ME YOU DIDN'T TRY AN EXPERIMENT ON YOUR OWN!"

"oh no, sorry, didn't mean ta scare ya. papy just spoke and i got excited."

Relief flooded through Gaster and his racing soul calmed. He had atomically feared the worst and he was so happy to hear nothing was wrong. "OH," he said simply, then what Sans had said hit him, "WAIT, HE SPOKE? WHAT DID HE SAY?"

Sans's smile couldn't possibly get any bigger as he said, "he said my name! well... he called me 'snans' but it was close enough."

"THAT'S WONDERFUL!" Gaster smiled, he was happy his youngest was finally talking and he was happy to know Papyrus's first word was his brother's name, it meant he loved him despite his terrible jokes. It was also a much better word than 'no.' Once Sans learnt it that was all he would say and he used it to defy any attempt to get him to do anything.

"let's go see if he'll do it again!" Sans took his father by the hand and began to drag him back inside and into his office where he'd left Papyrus in his play pen.

Gaster grabbed his camera and turned it on before giving Sans a quick nod. Sans smiled and picked Papyrus up. "come on bro, do it again!"

Papyrus looked at his brother and then at the camera, he looked hesitant and quickly buried his head into Sans's shoulder clearly a little shy about it.

"COME NOW, PAPYRUS," Gaster said trying to encourage him, "YOU'RE SUCH A SMART BOY, YOU CAN DO IT!"

"it's real easy, sa-ns, sans."

"S-SSS," Papyrus began, still hesitating, it probably wasn't a good idea to put him on the spot like this. Just as Gaster was beginning to give up Papyrus suddenly yelled out, "SNANS! SNANS! SNANS!"

Gaster almost melted at how cute it was; Papyrus yelling out his brother's name with his arms in the air, as Sans was hugging him. "OH MY GOD! SO PRECIOUS! MY BOYS ARE THE GREATEST!"

"papy is the greatest!"

"YOU BOTH ARE. MY AWESOME LITTLE BOYS, I'M SO PROUD."

Without turning the camera off Gaster came closer and placed the camera on the table before he pulled Sans and Papyrus in for a huge hug that Papyrus happily returned, Sans was still holding on to Papyrus but he lent his head forward showing his affection in another way.

When they broke apart Gaster turned off the camera and put it away while Sans put Papyrus back in his play pen. With a sigh Gaster unplugged his phone from where it was charging, he was beginning to get hungry but they were out of food in the lab, he looked over at Sans who was sitting on the floor next to the play pen watching Papyrus and writing in a file.

"SANS, DO YOU WANT TO ORDER A PIZZA? OR SHALL I SEE IF ANY OF MY FOLLOWERS HAVE INSTANT NOODLES OR SOMETHING?"

"pizza sounds good," Sans said as he put down his pencil and lay down on his back.

Gaster nodded and turned on his phone and was met with a lot of missed calls and voice mails. Curious but not surprised, (he always had a lot of missed calls from Asgore if he had his phone off of a while,) he played the first voicemail and unsurprisingly it was from Asgore.

"Howdy Gaster, I just got word another human has fallen. They appear to be quite hostile and have taken a few lives. I need you to put the lab on lock down. Don't worry about Grillby he and his family are safe and with me. The human shot a sentry dead and wounded another. The wounded man got everyone to evacuate so most people are safe. They seem to only be killing soldiers but please be safe and don't take any chances. Call me once you get this message."

Gaster was frozen with fear, causing Sans to look up at him in confusion, "dad? is something wrong?"

"SANS..." Gaster said slowly, "GO TO THE EMERGENCY CONTROLS AND LOCK DOWN THE LAB, NO ONE LEAVES, NO ONE ENTERS."

"dad?"

"NOW SANS!" Gaster snapped.

Sans jumped, seeing his father was serious he got up and ran to the terminal in the corner of the room, entered the passwords and locked the lab down, all lights in every room turned red signalling a state of emergency to everyone inside. There were drills for this so no one should panic. Sans didn't know what was going on but he watched his father closely trying to gain any ideas.

Gaster was listening to his other voicemails, he was really hoping the human was already dealt with. He was scared, even if the human was only going after soldiers there was still the fear that they'd get a taste for killing and go after civilians, children... his children.

Most of the voicemails were from his friends begging him to call them back.

Then he noticed a voicemail from Gerson. That wasn't good, the head of the Royal Guard rarely called him and considering the circumstances it couldn't be good. He didn't want to listen to it but he had to.

"Doctor Gaster, you need to call the King back. He's really worried about you and things are getting really bad. Undyne fought the human, saved some people by doing so but she lost an eye. It's bad Gaster, really bad. I had to retreat with her and now the human is headed your way. Please listen to me, lad, and don't do anything stupid, keep away from the human. Call the King."

That was the last message. He dropped the phone on the floor, his mind racing all he could think of was getting his kids out of here but he knew he was being stupid, the lab was under lock down, nothing could get in, they were safe. He'd just have to wait until the Royal Guards or the King took out the human.

"um, dad?"

"NOT NOW, SANS. I'M THINKING." Gaster didn't want to be harsh on his son but he had to think of a plan just in case.

"it's important," Sans insisted.

Gaster sighed and turned to Sans who was looking up at him, his eye-lights gone. "WHAT?"

"we shouldn't have locked down the lab."

"WHY?"

"human's in here."

Gaster pushed past Sans and looked at the security footage showing a young human about thirteen years old walking though the lab towards them, they had a cowboy hat on and a gun in their hand.

"SHIT..." Gaster took a deep breath. Once the lab was locked down there were several puzzles that needed solved to open the doors again, they were there to ensure that no one could get out until everything was safe but the human was here, they were not safe... "WE'LL BE OKAY, SANS. THEY'RE ONLY ATTACKING SOLDIERS, THEY'LL LEAVE US ALONE." If nothing else Gaster had to at least comfort his child, he had to know they were safe even if they weren't.

Gaster pulled Sans close and hugged him quickly before pushing him under the desk and then grabbing Papyrus and giving him to Sans. If the human came in then they wouldn't see them if they stayed hidden under the desk.

"dad? didn't you just say they won't hurt us?"

"THEY WON'T BUT IT DOESN'T HURT TO BE SAFE. JUST STAY OUT OF SIGHT AND KEEP YOUR BROTHER QUIET."

"what about you?"

"THEY'LL SEARCH THE ROOM IF THEY FIND IT EMPTY. I'LL TALK IT OUT WITH THEM, DON'T WORRY."

Sans looked really scared, Gaster forced what he hoped was a comforting smile and Sans nodded. Gaster then got to work hiding Papyrus's toys. He didn't want any evidence of children being there.

He just got done hiding everything when he heard the door open and he turned around fast and saw that a gun was being pointed at him. He threw his hands up and signed his words with his magical hands, "HUMAN, DON'T SHOOT, I'M NOT A THREAT TO YOU."

The human narrowed their eyes at him. "Beware the man who speaks in hands," they said, it sounded like they were quoting someone.

"WHAT?"

"The strange River Person said that to me. You are speaking in hands and yet you tell me you're no threat."

"I'M NOT. I DON'T KNOW WHY RIVER WOULD SAY THAT," he really didn't. He didn't know a lot about them, he'd only met them a couple of times but they knew he wasn't a threat so why would they tell a human to beware of him?

The human kept their gun pointed at him, "I don't believe you! You're a killer, you must be!"

"I AM A DOCTOR, A SCIENTIST. MY WORK IS TO BENEFIT THE UNDERGROUND, I WANT NO PART IN BLOODSHED."

The human approached slowly, never dropping their guard, they looked to his badge their face frowning in disgust. "You're the Royal Scientist? And you have the audacity to tell me you don't want bloodshed! Murderer! You experimented on humans! They deserve justice! You monsters must die for what you have done to the innocent!"

"WHOA, I'M NOT A MURDERER. I EXPERIMENTED ON SOULS NOT HUMANS THEY WERE ALREADY DEAD!"

"So? That's just as bad, you need to face justice!"

"I DIDN'T WANT TO! WE HAD TO DO SOMETHING! WE'RE TRAPPED DOWN HERE, HUMANS KILLED MY FAMILY, MY NIBLINGS! CHILDREN! THEY DESERVE JUSTICE TO!"

"The people who did that are long dead, you monsters live much longer than we do but there is no need to punish the descendants for the actions of our ancestors! You are in the wrong and you are not above consequences! You can't just use people like that!"

Gaster knew there was nothing he could say, this human was intent on killing him but he didn't want to kill them, especially with his sons in the room. He wanted another way, he wanted peace. He couldn't get through to them by talking but he had one last thing to try. "PLEASE, HAVE MERCY! I HAVE CHILDREN! I'M A SINGLE FATHER! WILL YOU SERIOUSLY LEAVE TWO YOUNG BOYS ORPHANED?"

"I don't care, their father is a murderer and they are better off with out you. Now face your sins!"

The human shot their gun, Gaster dodged and the bullet hit the wall but the loud bang of the gun was enough to make Papyrus start to cry, loudly and the fear that his father may have been shot was enough to make Sans come shooting out from his hiding place with Papyrus still in his arms.

"dad!"

"SANS, RUN! TAKE YOUR BROTHER AND RUN! GET OUT OF HERE!"

Sans hesitated, he didn't want to run, he wanted to help his father. He put Papyrus down and stepped between the human and his father, arms stretched out and both of his eyes glowing, flashing between blue and yellow. "leave my dad alone!" He snapped at the human.

"Out of the way, kid or I'll shoot you too!"

"SANS, PLEASE JUST GO, I'LL BE FINE!"

"no!" Sans was shaking with fear but he didn't give up, "i won't let you hurt my dad! he's a good person, he doesn't want to hurt anyone! he's showing you mercy, take it and leave!"

"Fine, you asked for it kid," the human looked crazed, a little too much LV, it had become too easy to kill, too easy to distance themselves and they'd kill anyone who got in the way of their justice. They aimed at Sans and shot.

Gaster turned Sans's soul blue and pulled him out of the way, not letting go of his soul, he pushed him towards Papyrus who was still crying in the corner, still too young to do anything to help, too young to understand what was going on.

Gaster put himself between his children and the human. "HOW DARE YOU! YOU COME IN HERE GOING ON ABOUT JUSTICE AND THEN YOU TRY TO KILL AN EIGHT YEAR OLD! WHAT'S WRONG WITH YOU?"

"He got in the way of justice, that must be punished."

"HE'S AN INNOCENT CHILD!"

"He's a monster!"

Gaster summoned a sharp bone in his hand, he gripped it like a knife and swung at the human, he didn't want to kill them, he just wanted to get them away from his sons. The make-shift weapon shattered into magic once it hit, but it was enough to make the human stumble back. Gaster shot out bone attacks at them but they dodged swiftly and countered with another shot that Gaster also dodged.

Sans was left stunned and lost on what to do. He'd never seen his father fight before, he was fast, really fast, his attacks hitting and dealing little damage but so quickly it didn't matter. He was dodging every hit to but Sans knew he couldn't dodge forever and he could tell his father didn't have the intent to kill the human by the little damaged that was being done, he knew his father could hit way harder if he wanted to. The human didn't have the intent to stop and accept mercy. Gaster was a powerful boss monster, high stats for a skeleton (who were known for being frail,) high LV, he was fast, he was smart, but he was going to lose because the human would not give up.

"dad!" Sans called as tears began to fill his eyes. He couldn't lose his father, he couldn't.

"WHAT ARE YOU STILL DOING HERE? GO!"

"i won't!"

Gaster ran towards him as he turned the human's soul blue and pushed them back. He grabbed Sans by the arm and began to drag him to the door.

"Stop!" the human called, gun pointed at Gaster, he kept moving all he cared about was getting Sans out of the room.

He briefly forgot about Papyrus. The human pointed their gun at the crying baby. "Stop or I'll shoot him!"

Gaster froze and turned, keeping a tight grip on Sans. "DON'T."

"I'll do it!"

"HE'S AN INFANT! YOU WANT JUSTICE? HOW IS KILLING A BABY JUSTICE!? THAT'S... THAT'S EVIL!"

The human frowned but ignored the comment, not answering the question. "I won't if you do as I say. If either of you get in the way of justice the baby dies."

"oh god..." Sans had never been so terrified in his life. It was bad enough that they were trying to kill his father but his baby brother... They couldn't. Not Papyrus, anyone but Papyrus.

"I'LL DO WHAT YOU WANT! PLEASE JUST HAVE MERCY ON MY CHILDREN!"

The human smirked, "On your knees, demon!"

Gaster did as he was told and got down on his knees, letting go of Sans as he did so. The human pointed the gun away from Papyrus and walked towards Gaster. They pressed the gun to his skull and Sans cried out, tears beginning to fall. "please, no! don't... don't hurt him!"

The human ignored Sans. "I'm passing judgement on you, monster. You are responsible for the deaths of many humans and you experimented on souls. The punishment is death. Any last words?"

Gaster closed his eyes, scared but accepting of death if it meant his boys could live. He only cared about them. "PLEASE, NOT IN FRONT OF MY SONS. DON'T TRAUMATISE THEM. LET THEM GO, LET THEM GET A FAIR DISTANCE AWAY, DON'T LET THEM HEAR IT."

The human hummed, thinking.

"PLEASE, THEY'RE JUST CHILDREN!"

"Fine, get! Shoo!"

"no! i won't let you hurt him!" Sans hugged his father. This couldn't be happening to him. He was afraid, devastated, he didn't want Gaster to die.

"SANS, PLEASE JUST GO. I'LL BE OKAY!"

"no you won't!"

"Go kid, before I change my mind and kill your father in front of you."

Gaster opened his eyes to take one last look at his child. His sweat little boy who had to leave him. "I LOVE YOU."

Sans sobbed, he couldn't leave his father but if he fought... He was as fragile as one could get, he'd die and then Papyrus would die. He wished Papyrus was older, he could fight, he was strong, but he was too young. Sans had no choice and he tore himself from Gaster and picked up Papyrus.

He took Papyrus out of the room and into the opposite one. He wasn't going to let his dad die but he had to make sure Papyrus was safe first. The human pointing the gun at Papyrus had scared him more than anything.

He wasn't going to lose anyone. He left Papyrus under a table and ran back, fear consuming him and tears falling. He got there just in time but had no time to think and acted on impulse, turning Gaster's soul blue and pulling him out of the way from the bullet causing it to simply graze his father's skull.

Gaster got up from the ground clearly confused and stared at Sans in horror. He didn't understand why Sans wouldn't just go! Didn't he know how dangerous this was!?

The human was mad. "That's it, I'm not showing any mercy to any of you skeletons! DIE!"

They aimed at Sans's chest...

BANG!

Gaster dove in the way of the bullet, it hit him in the top of the fibula in his left leg, breaking the bone in two, he screamed out in pain and grabbed the wound. He tired to get up, he couldn't; it hurt so much but he had to. He had to protect his child, Sans and Papyrus were all he had left. They had to live, Gaster couldn't watch another child die, especially a child that was related to him, especially his own. He tired again and pulled himself up, adrenaline the only thing keeping him going. He looked at Sans, who had fallen on his butt and was staring in horror at the human, the reality of the situation setting in on him. Then Gaster looked back to the human.

"I WILL NOT LET THIS CONTINUE. I GAVE YOU A CHANGE TO BE A GOOD PERSON BUT IT APPEARS THAT NOT EVERYONE CAN BE ONE. IT'S TIME FOR YOU TO DIE!"

Gaster raised his right arm as best he could while he was still bent over in pain, his left hand still clutching his wounded leg, he formed a blaster.

BANG!

Gaster leg go of his leg and grabbed his arm with a painful scream, a shot to the ulna, another bone snapped in two. The blaster fizzled out of existence.

Sans snapped out of it and got to his feet. He jumped in front of Gaster, his eyes glowing brighter. "human," he hissed out, "i won't let this go on. take another step forward or raise the gun again and you're REALLY not going to like what happens next."

It was a bluff, Sans knew he was weak, he had one ATK, he couldn't do more than one damage, if that. He'd never fought in his life, he wasn't fast like his father, he wasn't strong like Papyrus but the human didn't know that, maybe he could just scare them into surrendering.

The human took a step forward.

"do you wanna have a bad time?"

The human raised their gun.

Sans summoned his own blaster, it was small but it was still threatening. He'd just learnt how to summon one, he'd fired it only once and it had missed the target Gaster had set up and broke a window, Grillby's front window, the elemental was mad and Sans and Gaster had bolted away, only for Gaster to come back later to apologise and pay for it to get fixed.

Gaster, wounded and limping took the distraction Sans created, he gathered as much magic as he could.

The human began to squeeze the trigger, Sans shot first. He hit his target. One damage.

The human looked at Sans with a tilted head. "Ouch?" they said mockingly, "was that the 'bad time,' you promised? Pathetic. It's my turn now."

A huge blaster filled the room and Gaster smirked, his one eye glowing purple. "THAT WASN'T THE BAD TIME. THIS IS."

The blaster fired, the light was blinding and the human screamed. Gaster took the chance and sent several bone attacks forward before the beam stopped. Once the light of the beam faded Gaster and Sans saw the human laying dead on the floor, the yellow soul floating above their body, shaking.

"SANS, QUICKLY! THE CAPSULE!"

Sans didn't need to be told twice, he grabbed the capsule and sealed the soul away.

Gaster collapsed first, too exhausted and in too much pain to stay standing. Sans followed a second later, collapsing on his father, he to was exhausted and in shock, he couldn't get his mind around what had just happened. He couldn't think so he didn't and gave up on everything for a moment.

That was until Gaster spoke, voice shaking and weak. "WH-WHERE'S PAPY?"

"safe."

Gaster put an arm around his firstborn. "GOOD. WE NEED TO CALL ASGORE... AND I THINK I MIGHT NEED TO GO TO HOSPITAL."

Sans only nodded but didn't get up. He couldn't, he was still in shock and he wasn't processing what had happened.

He got up once Gaster passed out, after realising that his father didn't 'think he might need to go to hospital,' he did, desperately. He slowly picked up his father's now broken phone in a daze and called Asgore.

"heya, asgore, it's sans... yeah, i'm fine... yeah, papyrus is fine too... human's dead but dad's hurt really badly," he choked on a sob, he didn't even notice he was crying. "i need help, right now."