This is if Frisk doesn't believe the spider.
When you meet sans and papyrus, they give you an outfit that matches the in-game sprite from the original game. At first, though, your wearing a light brown tattered shirt and brown shorts. Frisk listens to sans's puns, and then goes through some puzzles, and fights Papyrus. When Papyrus goes on a Date,(or "hangout") He teaches Frisk to fly with her tiny wings. Then She fights Undyne and spares her to then later go hangout with her.
The core wasn't created so Gaster is still alive. He is still the Royal Scientist and Alphys is his apprentice. You learn that Gaster created a potion to give all the monsters wings. He was inspired by the birds on the surface. When Frisk enters the Lab, she hears Gaster and Alphys talking about the potion. Then he notices her and captures her. He was going to use her for tests because he knew he didn't give her a potion and yet she had wings. Luckily, Alphys stopped him and convinced him to let her go. Mettaton flies though the window and wants to do a game show. After the questions, He flies out through the same window he came in, posing (Fabulously!). Alphys and Gaster give Frisk a potion that makes Frisks wings healthy and strong. Then you meet Sans in the judgement hall and he talks to frisk about "not having LOVE, but having love." With his wings drooped down lazily. Then you fight Asgore, but Asriel shows up and wants to talk to his father to not fight the human. Everyone shows up and helps Frisk SPARE Asgore. But then, the Spider from the beginning takes to human souls and becomes OMEGA SPIDER. Frisk doges the attacks and •SAVES her friends. Then she spares the spider. Everyone is freed. Frisk convinced Asgore to set the humans and spiders free. Muffet thanks Frisk, and humans and monsters lives peacefully together again.
THE END
☻☺Sorry I took so long! My laptop died and I could't find my charger. I found it last night.☻☺