Alphys and Mettaton were busy at work. They needed Frisk back to her normal self, or Toriel was gonna kill them. Asgore wasn't happy either, but he wasn't as… vocal, about it. Sans often came down to help. They wanted Frisk back just as much as Toriel did. This particular Sans visit wasn't so pleasant.
"SHE'S GONE!"
Mettaton and Alphys just stared in disbelief.
"Sans? What do you mean she's gone?"
"I mean, she's GONE! I got up and went to retrieve her from the drawer, and she wasn't there. I searched everywhere, she's gone!"
Alphys was in a panic mode at the moment. She had an idea, but it wasn't one she liked.
"What if she shrunk more?"
"Alphys, darling. I hope very much that you're wrong, though you might not be. Because if she shrunk more, she is even more vulnerable to everything this world has to offer. Because of my increased vision due to my mechanical zoom mechanisms (Really good at seeing small things), I'll go look for Frisk. Sans, you stay here and Help Alphys to counteract the growth serum."
It didn't take him long to spot her. She didn't shrink; he was just looking in the wrong drawer. He figured he missed something because all he heard was a hearty 'eureka!' as he walked in.
"Did I miss something?"
It turns out that while he was retrieving Frisk, they had reversed the formula, creating a growth serum instead. Excited, Mettaton placed Frisk on the counter. Alphys carefully put a drop on her head and they stepped back. There was a large puff of what they thought may have been smoke. They were all excited as Alphys asked Frisk some follow up questions. Sans called Asgore, he was afraid to speak with Toriel at the moment. He came to pick her up a half hour later.
The End!
(Yeah, that's it!)