The monster king was getting lonely…really lonely, no woman in the monster land has met up to his demands or standers at all. He had to do something, he needed to keep his monster bloodline alive, without it the humans would take over and kill all the monsters off the face of the earth. So he did what he needed to do. He went to the humans castle to your hand in marriage

You were human…well at least you thought(make your own lore to that) you were the princess of your kingdom, but the thing was no prince/man could stand up to your standards/demends. You sat at your throne like the pretty princess you were, when you heard frightened scream in your halls. Walked in the throne room was the monster king, with his 2 soldiers as your soldiers stood on guard