Aura Sight

Aura Sight is one of many secrets skills the Professor possesses.

As its name imply, it is an ability that help discern auras. It works on human, enabling Theo to discern the true nature of each character and make sure they are who they claim or seem to be, but it also works on some objects.

This skill is also useful as it works on the Shadowy Figures. It's the reason Theo was able to confirm the strange Shadows seen by the group were actually themselves, even though the color of their auras were less bright than the originals. It also seems to highlight residual auras, like in the trunk of the Corolla.

Most of the auras he's able to see are unicolor; His own is bright green, Trick's aura is purple. Emma has a blue aura while Brian's is red. Adisa Bellow aura was light blue. Once someone awakens, their aura has a dark shadowy tinge to it as well.

Briar Anam is the only exception, having a Yellow-Orange aura, as told in There Came A Knocking.

The Professor discover this aptitude while reading. By zoning out, concentrating his sight on "what's not there", the spaces between the letter, he start seeing glimpse of auras. He kept practicing until he gain a certain mastery over it.