The forces of good and evil are related

[Foxaèr]

This is purely from a fictional, metaphorical viewpoint.

I have read lots of books, seen lots of movies, seen lots of television shows in my lifetime.

Take the bible, for starters. God, the force of good and his creation, could be considered his son, the devil as force of evil.

Now onto Star Wars. Luke Skywalker, the force of good while Darth Vader, the father, is the force of evil.

Now onto the television show "Lucifer". God, the force of good. Lucifer, the son, the force of evil. Lucifer's mother, God's wife, also somewhat a force of evil.

The television show "Supernatural". God, the force of good. Darkness, God's sister, the force of evil.

Stephen King's "The Shining". The force of good in the young son. The force of evil being the father.

I suppose we choose the familial connection for good and evil as it resonates more with us in how we personally relate to our own families, unless one is of the rare statistic of having been part of the "perfect" family.