With Muffet away on her blind date, Frisk decided to take this opportunity to explore the house. They searched a few cupboards in the kitchen, finding some pieces of saltwater spider taffy. Placing it in their pocket, Frisk then searched the pantry, finding mostly spiders and food made of spiders.
After that, they wandered around for a bit before finding the door to the basement. Pulling the door open, Frisk descended the stairs to the darkness. Reaching into their pocket, they pulled out an old-fashioned lighter, usually used to light candles, fireworks, or Muffet's huge cigar. Frisk flicked the wheel and the lighter flared to life, lighting up the darkness.
They searched the rather expansive basement for a while, encountering among other things, a large purple cannon, a pile of purple bombs, a pile of cookbooks, countless cobwebs, an old distillery, and a huge monster that seemed to be a combination between a cupcake and a spider.
Frisk recognized them as Mr. Tuffet, Muffet's loyal pet. He wasn't the first Mr. Tuffet, though. The Mr. Tuffets before him had variably been blown up, eaten, blasted off to who-knows-where, squished, rolled into a cigar, disintegrated, or met their end in various other ways. Muffet didn't seem to mind that much, simply cooking up another Mr. Tuffet.
Frisk tip-toed carefully, trying not to arouse Mr. Tuffet's attention. Sure, being made mostly of pastry meant that Mr. Tuffet wasn't able to do much harm even if he ate Frisk, but waiting to get spat back out could get annoying.
Frisk carefully made their way around Mr. Tuffet, managing to avoid being spotted. They sighed in relief as they continued walking, before they heard a sizzling sound.
Frisk looked over and say that they had accidentally lit a nearby pile of bombs with their lighter. Frisk could only groan before a the bombs blew up in their face in a loud explosion that shook the house.
When the explosion cleared, Frisk was left covered in soot and with charred hair. They then noticed that Mr. Tuffet had been alerted by the explosion, and was now looking at them with a cheerful hunger. Frisk sighed in annoyance as they sprinted out of the basement.