As Mettaton was in the kitchen, feeding Alphys, Asriel and Frisk were in the living room, playing a board game. Asriel picked up the dice and rolled them.
"Four," Asriel said, reaching for his game piece. "Huh?" He said, confused. The piece was gone. He looked at Frisk to see she was gumming on it. "Hey, that's not a chew toy, silly!" Asriel said, taking the piece from her. Frisk whimpered and reached for it. She then got an idea and grabbed one of Asriel's ears. She began to gum on it, soaking it in drool. Asriel giggled, cringing a bit. "That's my ear!" he said, giggling. Frisk giggled and blew a raspberry at him. Asriel smirked and started tickling Frisk. Frisk squealed with laughter and kicked her legs. Asriel smiled. Frisk looked at him and crawled into his lap. She hugged him tightly.
Alphys awoke in her room. She looked around, confused and curious. Her regressed mind remembering almost nothing. She sat up and slowly climbed off of her bed. She was about to crawl out of her room when she heard the front door open.
"I'm home!" A deep voice echoed through the house. Alphys heard this and whimpered. She crawled under her bed and curled up. A few minutes later, she heard someone walk into the room.
"Alphy darling, did you wake up?" Mettaton's voice called. "Alphys?" He called, noticing she wasn't in her bed. Mettaton looked around. He soon spotted Alphys's tail sticking out from under her bed. "Oh, there you are," Mettaton said, gently pulling her out from under the bed. Alphys whimpered. Mettaton saw tears in her eyes and picked her up. "What's wrong darling?" He asked.
"Excuse me," a voice said behind them. Mettaton turned around to see King Asgore standing in the doorway.
"Oh, hello Asgore," Mettaton said. "I didn't expect you to return while I was here."
"Hello Mettaton, nice to see you," Asgore replied. "Might I ask what has happened here? I walked in to find that everyone has been regressed to the age of toddlers."
"Oh, just a small accident is all," Mettaton said, rocking Alphys, who was still crying.
"Oh goodness," Asgore said, looking at Alphys. "The doctor looks younger than all of them."
"She just had a greater exposure to what the others have had," Mettaton said, looking in Alphys's pockets for a pacifier.
"What's got her so upset?" Asgore asked.
"I'm not entirely sure," Mettaton said. "Her mind is the same age as her body, so she's pretty much a baby."
"Oh. I see," Asgore said.
"Dad!" Asriel shouted, running into the room. He hugged Asgore, smiling.
"A-Asriel!?" Asgore blurted out in shock. Toriel walked in and explained what had happened to Asgore. Asgore picked up his son and hugged him tightly, tears rolling down his cheeks. "Asriel, my son. I've missed you so much!" He said.
"I missed you too Dad!" Asriel said. "I'm so sorry for everything I did as a flower!"
"No my son. Do not be sorry. You didn't have a soul as a flower. You do not have anything to be sorry for," Asgore said. A loud scream interrupted them. Asgore and Asriel both looked over at Alphys. She was screaming and sobbing, squirming in Mettaton's arms. Mettaton was trying his best to calm her down, but no matter what he did, she just cried. Asgore walked over and looks at Alphys. He hugged Asriel tightly before setting him down. "Hand her to me, please," he said to Mettaton. Mettaton handed Alphys to Asgore, who hugged her trying to calm her down. Alphys just continued to sob. Asgore lifted up her lab coat to see that she was wearing a diaper. He checked it before handing Alphys back to Mettaton. "Diaper rash," he said. "She needs changed."
"O-Oh," Mettaton said, quickly holding the sobbing lizard at arms-length.
"D-Dada!" Alphys sobbed, reaching her tiny hands out to Mettaton, wanting to be hugged. "H-Hold on, d-darling, you need changed f-first," Mettaton said, keeping Alphys away from him.
"Oh come now, it's just a wet diaper," Asgore said. "No need to make a big deal out of it." Mettaton sighed and took Alphys to the bathroom. He still wasn't that comfortable with changing diapers, but at the same time, he didn't want to have to listen to a baby cry continuously. He set Alphys down and began to change her.
Darkness surrounded Frisk as she walked through a never ending hall. She was unsure of where she was and where she was going. But an uneasy feeling was present throughout the darkness. Suddenly, a figure became noticeable in the dark. A young girl stood ahead. She was looking at the ground. Her short brown hair covered her face. She wore shorts, and a green and yellow striped shirt which was covered in blood and dust. In her hand, the blade of a large knife glistened in the darkness.
"Hello," the girl said, looking up. "I'm Chara." The girl smiled, her red pupils shining. Frisk stepped back in fear. "What? You don't know how to talk to someone?" Chara said, giggling. "Anyways. You have something that I want," she said. "And this time, I'm going to take it without giving you a choice." Chara laughed and lunged at Frisk. Then everything went dark…
Frisk awoke in her bed, crying. Asriel ran in and picked her up.
"Frisk, what's wrong?" He asked, hugging Frisk. "Did you have a bad dream?" Frisk nodded and buried her face into Asriel's shoulder. She suddenly had a strange feeling. Something was inside of her soul. A presence of something, or someone. This feeling was immediately replaced by nothing, as Frisk lost control of her mind and soul. That presence in her soul now controlled her. Frisk looked up at Asriel. Her pupils now had a red tint in them.
"Hello, Asriel," She spoke. Her voice sounded distorted. Asriel looked at her in shock.
"F-Frisk?" He whimpered. Frisk just giggled.
"You're wrong, Asriel. It's me, your best friend…"