"What?" Frisk asks.

"Reset," Sans replies, "before it's to late!"

"Sans are you OK?" Frisk asks.

"I can explain in the next one. Just reset, before they hurt you."

"Who?"

"Later!"

"OK! I'm on it!"

Frisk summons the reset button and presses it. There's a moment of awkward silence.

"It didn't work," Frisk explains.

"Cmon' kid," Sans pleads, "stay DETERMINED."

"I am DETERMINED! I'm always DETERMINED!" Frisk replies.

"Oh god, it must be Gaster." Sans replies.

"Who?" Frisk asks.

"My dad," Sans explains, "he fell into the core, but I had a device that ran on DETERMINATION... to power it I killed criminals and took their souls. Starting with that bully at your school. Then, I- I-"

"It's OK Sans," Frisk replies, "I'll just talk to Gaster."

Frisk begins to walk away. Sans grabs their arm. "Frisk," Sans pleads, "you have to kill Gaster."

"I can't do that," Frisk replies, "I'm sure he can be reasoned with. After all, he's your dad. If he won't listen to me, he'll listen to you."

"Frisk please!" Sans yells, "I've hurt so many people. Hundreds are dead because of me. I murdered an innocent monster in cold blood. I just want to reset. I just want this nightmare to be over."

"Sans," Frisk tries to comfort him, "it'll be OK. I promise. I'll save everyone. As soon as I reach Snowdin next time, I'll use my DETERMINATION to revive Gaster. It'll be OK. Listien, we can't worry the others. Let's head to Mettaton's musical as if nothing is wrong. You did remember about that right?"

"Nope!" Sans replies,"but hey I'm kinda a BONE HEAD."

Frisk and Sans snicker.

"Toriel and I are just about to leave. Meet me there. I'll be in the front row. I'll save you a seat."

Toriel walks outside. "Ready to go Frisk?" She asks.

"Yup!" Frisk replies, "see you there Sans!" Toriel and Frisk get in their car.

"You going Sans?" Toriel asks.

"I'll meet you there," Sans replies.

Toriel smiles and drives off. Frisk says in sign language through the window, "it'll be OK. We can still fix this." Sans begins to fell batter, but then Chara soils his good mood.

"You can't help them," Chara grins, "I'm going to take Frisk's soul. Then I'll be free at last!"

"I'd like to see you try," Sans growls.

"I already have a tight grip on your soul," Chara maliciously chuckles, "next time you FIGHT, it's over."

Sans ignores them. They head to the theater. They meet up with Frisk.

"So what's the plan?" Sans asks whispering, "you got anything?"

"No," Frisk replies, "not really. I'll just show him MERCY and work from there."

They get into the theater and the play starts. Only a few minutes later, the lights go out. The room, including the stage, is pitch black.

"So," Gaster laughs from seemingly everywhere,"you thought you could buy time by ignoring me? No, all I need is one more human soul to surpass Frisk, but that's not my only goal. I made a promise to an old friend. You better run Frisk." Frisk's soul turns green.

"Oh wait," Gaster grins, "you can't."

"Hey!" Mettaton yells, "you can mess with my performance, you can frighten my fans, but you threaten Frisk, and you deal with me!"

Gaster laughs,"very well. I see all your friends are here Frisk. Well, say goodbye."

Sans quickly turns Frisk's soul blue, making it both blue and green, and throws them down. Gaster Blasters butcher the crowd, monsters and humans alike. Sans manages to douge, but everyone else, everyone Frisk cared about and loved, are all dead. Dust and human souls fill the room."

Sans knows he only has one shot. He has to kill Gaster in a single attack. "Frisk," Sans pleads, "after this, kill me and Gaster and reset."

"What?" Frisk asks. Sans takes the blue out of Frisk's soul. He FIGHTS Gaster with everything he has. In a long, brutal attack. Until finally, he uses his special attack.

"That old trick?" Gaster asks, "I thought you could do better than that! You didn't even damage me!"

Frisk begins to sneak up on Gaster, holding the stick they had in the Underground. Gaster notices them and attacks. Sans ends his turn to ACT and turn Frisk's soul blue, causing them to fall, and the attack to miss.

Chara grins. Sans loses control. He tries to think about his loved ones, but they're all dead. Sans surrenders.

Chara laughs. "OK kid!" They gleefully cry, "let's see how bad blood stains that striped shirt of yours!"

Frisk ACTS. They can check, cry, plead, or surrender. Frisk checks Gaster.

W. D. Gaster. 666666 atk, 666666 def. He wants your soul, and he's not letting you go away.

"Goodbye kid," Gaster grins. Gaster and Chara attack. Frisk narrowly douges. They check Chara.

Chara. 1000 atk, 1000 def. Who know Sans could be so strong? He's given up. It's up to you now.

They attack again, Frisk douges, but the attacks get closer.

Frisk pleads, saying "just let me reset, I can revive you."

"Why do that?" Gaster asks, "when I can kill you and reset myself? I'll never have to be revived again." They attack again, growing ever closer.

Frisk cries out for help. Sans tries to fight back... "but nobody came," Chara grins.

The duo attacks again. The next attack will hit for sure. Frisk offers MERCY.

"You know what," Gaster grins maliciously, "this is silly. You're right. Let's quit fighting." Sans sees the battle through Chara's eyes. He notices Grilby's Glasses on Gaster. He used them when he was learning to dunk.

"Frisk stop!" Sans yells, "it's a trap! He'll dunk you!" Sans fights back desperately, but it doesn't work.

Gaster offers Frisk a hug. Frisk accepts. Gaster grabs Frisk by the throat and chokes them. Chara finishes them off with a Gaster Blaster. In their last moments of life, Gaster whispers to them,"get dunked on."

Chara takes the soul. "Finally," they smile, "I can love again. I don't have to hurt people."

Gaster hugs Chara. "Good to have you back," he smiles, "ready to reset?" Chara nods. Gaster absorbs the human souls, and summons the button. "Oh," he hesitates, "and Sans, I'm sorry, but don't worry, it's all over now. I'll never have to hurt you again." Gaster resets.

Sans wakes up, screaming. He goes downstairs. it's eight in the morning. He hears the sizzling sound of bacon. He sees Gaster cooking. "Good morning brother!" Papayrus smiles, "how did you sleep?"

Sans's eye glows blue. He glares at Gaster, but Gaster responds with a smile. "Something on your mind son?" Gaster asks.

"No," Sans grits his teeth, "I'm fine."

"We'll discuss the previous reset later," Gaster whispers, "what do you want for breakfast?"

"Ketchup," Sans replies. Grilby tosses him a bottle. There's some writing on the back, it reads, "brace yourself son, you're technically from another timeline, but your memories should correct themselves by the time you finish reading this. Don't worry about your old memories, they won't be effected. I wouldn't rob you of your memories of your little friend. Let's see... should start in 3... 2... 1... now."

Memories come flooding in. Memories of a new timeline, where Gaster is still alive, but Sans vows he won't be for long...

Meanwhile, a child has fallen into the Underground. Landing on a bed of golden flowers, but this child is not Frisk, this child is Chara...

Hello! Gen3king here! Before you ask, no, this isn't the end. Just to clarify. Also, I may recreate the fight against Gaster and Chara in unitale, and add different endings, but if anyone else wants to give it a shot I say go for it. Just do me a small favor and send me a link, cause I'd love to try them out. Also, any feedback? All feedback is appreciated. Thanks!