Jealousy might be a motive. If the young adult is achieving things that she never could, like having a lot of friends or being successful at school, her obesity - related insecurities could turn into jealousy. So she uses abuse to try to hold the young adult back and make herself feel better in a twisted way.
Perhaps she feels powerless in other aspects of her life, like her marriage or career. Her obesity might contribute to this feeling of powerlessness. And abusing her child makes her feel like she has some control, at least in the family dynamic. In a young adult novel, this could be explored through the young adult's growing awareness of their mother's complex motives.
She could be shown as a controlling figure. For example, she might restrict the protagonist's freedom, not allowing them to pursue their dreams or have normal social interactions because of her own insecurities related to her obesity. This could lead to the young adult feeling trapped and constantly under stress.
On the contrary, positive fanfiction can inspire and uplift. Instead of delving into 'abusive mother fanfiction', exploring stories about healthy family relationships can have a positive influence on our emotional well - being. It can give us models of good communication, love, and support within families, which is much more valuable.
Another motive could be the build - up of years of emotional abuse. She might have felt so trapped and hopeless that killing him seemed like the only way to end her misery.
One possible motive could be financial difficulties. For example, if an adult has lost their job and has no other source of income, they might turn to bank robbery in a moment of desperation. They may have debts to pay off and see the bank as an easy target to get a large sum of money quickly.
Jealousy could be a motive. Maybe she suspected her husband of infidelity and in a fit of rage, committed murder.
One possible motive could be protection. The mother may want to shield her family from a painful truth.
One motive could be shock value. Filmmakers know that the idea of one human eating another is extremely disturbing and it can immediately grab the audience's attention. For example, in movies like 'Cannibal Holocaust', it uses this extreme concept to shock the viewers and create a sense of horror.
Some might spread these stories out of boredom. They have nothing better to do and they think that creating a story about seduction at an adult theater will amuse them and their friends. Also, there could be a bit of envy involved. Maybe someone is jealous of the people who go to adult theaters and they create these negative stories as a way to put down those who frequent such places.
One motive could be financial gain. In some stories, the young man might see the older woman as a source of financial stability. For example, if she is a successful businesswoman, he may be attracted to the lifestyle she can provide. However, this is a rather negative and stereotypical motive.
Another motive could be power. In a social or domestic context, the older woman may feel a need to assert her power over the younger one. By seducing the young housewife, she gains control over her actions and decisions, and this gives her a sense of superiority. Also, it could be about companionship. Maybe the older woman is lonely and sees the young housewife as someone who can fill that void in her life.