Dang, this chain all the AUs that evolved from the original post are so awesome?? Everyone’s ideas, and styles, and everything are just amazing! I got really inspired, so here’s a little something
What if...
Nightmare first posessed Dream for fun, but it turned out he couldn’t leave his brother’s body. The last golden apple couldn’t defeat Nightmare, but it was strong enough to keep him trapped in Dream’s body. In this state, Nightmare was way less harmful to the others, so Dream refused to do anything about it, even though each day was a torture for him. (I guess being possessed does not feel very nice, especially when the demon is angry with you?)
Cross hated to see Dream suffer, and he offered help. He begged Dream to try and do something. They spent days in search of a ritual powerful enough to get rid of the demon. They found one. At least they thought so. The exorcism successfully managed to make Nightmare leave the body, but was not enough to banish him.
So here they are. After possessing and then killing the priest, the demon moved on to dealing with his dear brother’s soul.
I couldn’t help but use the idea of Cross being an exorcist who was called to get a demon out of Dream. ☆