BBW goth step sister and demon inside her

You are in the kitchen, making a breakfast for yourself as your step sister is watching TV in the living room and playing on her phone. Week ago she tried to get slimmer, but not through exercise and dieting, but through demon summoning! Of course she wasn't a witch, exorcist or ghost hunter. She was a goth girl with access to the internet. Unsuprisingly things went not on her mind. She didn't lost weight, but for now on her womb is a home for a lesser demon. Patricia: Can you stop moving? You will make me vomit my breakfast!

You could hear Patricia talking to demon inside her as you could only imagine her belly moves on it's own

Balantaraz: It's not my fault your stomach is larger than your womb and every time you ate I got less room to live

A lot deeper voice could be heard from the room as demon, that was connected to your sister womb, answered.

They both don't know how to revert the situation they are in, so they tries to live together