I don’t think Shelley has any motivation beyond being psychotic. I can’t imagine her writing romance novels based on how she speaks to her brother, daughter, husband, etc. She does not seem to have a grip on reality or others desires or wishes. Her husband acts just as out of touch with reality and her daughter eats everything. This family could be set in a horror movie on par with the family from Texas Chainsaw Massacre. A sequel should be made.