Gaster looked at the letter. He needed to stay late for a science convention. Oh dear, how would his kids react with his classes to teach and his sons to take care of? No matter, Gaster thought. I'll just get a sitter for the boys who can function as a substitute teacher. It couldn't be that hard to get a person who had qualifications to teach and baybsit.

And it wasn't! The problem was the monsters that Gaster took care of, terrified others. It wasn't Undyne, or Asgore, or Asgore's betrothed Toriel, otherwise Gerson would've been an easy grab. No it was his sons. Papyrus was known for his cooking skills such as the Dangerous Pie incident where Papyrus tried to make Pie with the Gaster Blasters. Sans, on the other hand, was known for his terrifying pranks such as the time he nearly put out one of his friends's father. "it was just a little water." Sans had defended. But right now Grillby was on a ban from seeing Sans.

So Gaster was out of ideas. Until Gerson told him to put an ad in a paper and put it around the Underground. That's what Gaster did.

A couple of days later, a monotone voice called him. "Hello, I saw your ad around Waterfall, are you still looking for a sitter to come today?"

"Oh, Yes I am! But I have some questions first."

"Okay."

"Have you ever taught before?"

"I'm certified."

"Have you taken care of children before?"

"I've had to take care of 2 children every day."

"On a scale of 1 to 10, how scared are you of the 2 infamous skeleton brothers?"

"1." The voice was defiant like another person that Gaster never wanted to see again. But the person was never this monotone, so Gaster trusted them.

"Alright. Could you be here around 7?"

"Yes, I can make my way over there."

"Thank you." Gaster called in his students. "Now class, I've found a substitute for my absense for a while. They will be here soon. Now I need to lay down some rules. No wrestling."

Undyne pouted.

"No pranks."

Sans crossed his arms.

"No cooking."

Papyrus looked down.

"No Anime theories."

Alphys knitted her eyebrows together.

"No fighting."

Asgore nodded.

"And no fire."

Toriel dipped her head.

"Get it?"

"Got it!" The class nodded.

"Good." Gaster heard the doorbell ring and the class went around to see the person who would be Gaster's substitute. He opened the door to nearly choke on air. "Ch-chara!?"