Personal horror: Alienation
You body is a thing you can change daily. It stopped defining you a long time ago. Even sex is not a thing of the past: you can be male at breakfast on Luna, female at lunchtime on Mars, and a whale swimming in the Sun in the evening.
Your mind can be saved and stored, you can erase those painful memories, you can fork yourself and have many version of yourself running around. Who are you? What have you become?
The opposition to the player characters could be the player characters. They were just forks trying to stop what they saw as forks of themselves doing things against their wishes. Who is the original? Who is the fork? Does it even matter?