Another option is a time - travel fantasy. For example, a character could travel back in time to ancient civilizations like the Maya or the Roman Empire. They could experience the culture, architecture, and daily life of those times, and perhaps even change the course of history in some small way.
Using that expression is not proper. Here is a story of a loving mother. A mother always cooked her child's favorite meals. When the child had to move away for college, she sent care packages full of home - cooked goodies regularly. She would also write long letters with words of encouragement and love, which made the child feel that her love was always there no matter how far away.
In a civilized society, we uphold values such as respect, family harmony and propriety. 'Cum in step mom stories' clearly violate these values and thus have no place in literature.