Origin

When she was just a girl, her village was attacked by otherdimensional monsters who appeared through portals. She fled from them and accidentally fell into one of those portals. While falling in this dimension, she prayed to her goddess. The unspeakable being known as Godhead appeared to her and transformed her into Hell Sonja, making her the ruler of this new dimension. She quickly realized that the souls sent to her dimension were those slaughtered by her otherdimensional counterparts.

Sonjaversal

One of her otherdimensional counterparts, Saint Sonja, reasoned that Red Sonja had forsaken her god and thus was punished to afterlife. Sending other variants after Red Sonja, she was unable to kill Red Sonja. Thus she gathered all other Red Sonja variants including Red Sonja herself at Hell Sonja's dimension, ordering the variants to kill the original Red Sonja. Sensing something was amiss, the variants rebelled and travelled to the place where their gods resided. Red Sonja killed her god and thus the barriers of Hell weakened. Many of the souls escaped Hell and returned to live. Weakened, Hell Sonja then set out to visit Red Sonja variants, such as Blue Sonja, Sonja Noir, Yellow Sonja and Purple Sonja, to get them to kill their adversaries again, so that Hell once again was full of souls.