User blog comment:Zathronas/Speculative Author - RWBY Relativity/@comment-25396609-20160225025456/@comment-25396609-20160225032141

Simple facts; aura is understood by science, and can be measured by technology.

This is proven by the fact that Atlas is experimenting with it, and have created a synthetic being capable of generating an aura. a machine with a soul.

A machine generating a soul can be explained in several ways, the simplest of which is having an artificial neural system equivalent to that of a human brain and CNS.

Magic is magic, doesn't need an explanation because it is what it is. The maidens power is magic as well, but it was specifically created in a state where it was entangled with a human soul. Seeking out a new host based on its previous owners final thoughts a byproduct of the way it was createdm and only accepting specific individuals as hosts (young women) because the old wizard first gave it to individuals who fit the description.

Grimm sensing negative emotion is simple, responses like fear and anger generate a far more powerful spike in neurological activity than positive emotions do. They trigger our most basic instinct; fight or flight. When we enter a fight or flight state, we become more aware of our surroundings, process more information faster, and have a massive increase of electrical signals traveling through our bodies.

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My theory, while a bit far-fetched, does have a fair bit of reasoning behind it I haven't fully explained here.