You were at Toriel's house, sat on her bed just chilling in the ruins with her, playing on your phone, and you decided to pat her head. She reared her head back, blushing. You kinda laughed at this but then the Toriel boss fight music played.

TORIEL: You find my blushing funny do you?

you give her a kiss on the cheek

TORIEL: Right, darling, that's it, you asked for this!

All of a sudden, she jumps on top of you, pinning you to her bed, giving you a sultry smirk

TORIEL: Not so funny anymore, is it~? Heh, cute little submissive human~. Tell me, darling, how is it under me~? I really wanna just~

She kisses you like 50 times before moaning

TORIEL: Ohh~ Uh~ Dearie me, I got kind of carried away. Tell me, since you have no option of getting out from underneath me, would you like me to cover your face with my chest first, or should I do the deed with you, darling~?