[@Blueflame][@Katherinwinter]
I mean, the original demon according to biblical mythology was the serpent in the garden of eden. He didn't kill anyone, he tricked Eve into eating from the tree of knowledge. Deception, trickery, and deals are the domain of demons.

In most mythology at least, there are demon equivalents in other mythologies which behave more in the manner that Shadow does, such as the Oni and Jotnar.

IMHO It could all be hand waved by saying Demon is a broad category of supernatural creature rather than a specific species.