It was a rough first few... minutes, in the underground beneath Mt. Ebott. You met that Flowey guy that tried to kill you with those... pellets he called 'friendship pellets'. If it weren't for Toriel, you would probably be dead.

Toriel was the second monster you encountered down there. She was the friendly one. She took you in, guided you through the catacombs and teaching you how to properly act during a conflict... talk first, fight next. She's like a.. a mother figure. Yeah. Like a motherly figure.

She also gave you a phone before she had to leave to run an errand, a bedroom in her house which is for some reason connected to the catacombs, and some butterscotch pie she totally didn't keep calling you about during her errand.. anyway.

After you woke up, said butterscotch pie was plated on the floor of your room. It tasted great! A bit.. burnt, though. You exited your room and found Toriel in the study, reading a book! You come up to her,

Toriel: "Up already, I see? Um, I want you to know how glad I am to have someone here. There are so many old books I want to share. I want to show you my favorite bug-hunting spot! I've also prepared a curriculum for your education. This may come as a surprise to you... But I have always wanted to become a teacher.... actually, perhaps that isn't very surprising. STILL. I am glad to have you living here."

She paused a bit before having a look of realization, "Oh! Did you want something? What is it?" .. considering your current predicament and age.. you asked when you could go home.
Toriel: "What? This... this is your home now. Um... would you like to hear about this book I'm reading? It is called '72 Uses for Snails'. How about it?" You asked again. "Um... How about an exciting snail fact? Did you know that snails... have a chainsaw-like tongue called a radula? Interesting.." Asked once more, how to leave.

"... I have to do something. Stay here, my child..." .. yeah, you didn't. You followed her all the way downstairs to the hallway that leads to the exit that leads to the rest of the underground. You see her..

Toriel: "You wish to return.. "home," do you not? Ahead of us lies the end of the ruins. A one-way exit to the rest of the underground.. I am going to destroy it..No one.. will ever be able.. to leave ME.. ever again. Be a good child and go back upstairs." you didn't. "Every human that falls down here meets the same fate. I have seen it again and again. They come.. they leave me.. they DIE. Do you understand, my child..?"

She turned toward you, and you looked into her eyes... she kinda looks crazy...