Debriefing The Findings (2)

"From what I have managed to gather from the texts, a lot of things that we knew about the demons were... slightly incorrect, to say the least," Jonus replied.

"Like what?" Rose questions. 

"Well, for example, the origins of the demons.  Although they do appear to come from a different world, they come from within our own universe, like those creatures, I mentioned."

"Really?"

"Yes. When one usually thinks of demons, one assumes them to be a sort of evil entity, spreading across many worlds, and killing whatever it sees. However, after reading the texts, this may not be the case.

I think it is more helpful to think of them as invasive species, that migrate across the land to settle in new areas and increase their population. As they migrate, they displace and kill many of the native wildlife that had been there for millennia.