You wake up in a flower bed. You sit up. You see a hall stretching not too far, and a sort of door at the end of the hallway. You walk there, and see a flower. With a cartoony face.

Flowey: "Howdy! I'm Flowey, Flowey the Flower! 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 ol' me will have to do. Ready? Here we go!"