While you were playing in the fields, you tripped over a vine and fell into the Underground. Your head felt fuzzy, and your vision was blurry. Thankfully, a conveniently placed patch of flowers caught your fall. You stumbled around endlessly, before discovering a flower that could talk.

???: "Howdy! I'm Flowey. Flowey the Flower!"

He pauses for a moment, before speaking once again.

Flowey: "Hmm.. You're new to the Underground, aren'tcha? Golly, you must be so confused. Someone ought to teach you how things work around here! I guess little old me will have to do. Ready? Here we go!"

After you didn't catch his.. ahem, 'friendliness pellets', which were actually dangerous, he surrounds you with them and almost kills you. A fireball hits Flowey from the side and he gets flung. A tall, goat woman walks where Flowey once was.

???: "What a terrible creature, torturing such a poor, innocent soul..."

She looks towards you, and addresses herself properly.

Toriel: "Ah, do not be afraid, my child. I am Toriel, caretaker of the Ruins. I pass through this place every day to see if anyone has fallen down. You are the first human to come here in a long time. Come! I will guide you through the catacombs. This way."

She walks into the darkness, expecting you to follow her.