A Shadow is a parasitic alien creature first tested on lab rodents by Silas Charnon whose only purpose and desire seems to be to cause havoc and mayhem. They possess malevolent intelligence, having been known to strategize and think. A good example of this creature is Sybrian. Sybrian was in Emily's way, stopping her from saving her mother, and she unwittingly cured Trellis of him in the process of defeating him. In the book Escape from Lucien, Navin and his allies on the Project Colossus that was destroyed by the Elf King's warship encounter these shadows when they fall into Lucien, Robert being a victim of their possession. They are saved from them by Riva Ash, mayor of Underground Lucien. Shadows are also known as Dark Scouts, and have changed color through the books. It is believed that Shadows change appearence depending on where they are. For example, Typhon Shadows are purple, and are small. Alledian Shadows are blue,and bigger than Typhon Shadows.
In book 6, "Escape From Lucien" , Navin, General Isaak Pil, and Alyson Hunter take it upon themselves to fend off the Shadows until the citizens evacuate. They don mechs called vacbots and suck the mostly gaseous Shadows up into their glass containers. However, this measure is only temporary, as even one Shadow has been known to crack glass. Emily alone seems to be able to use the power of her amulet to cure people of Shadow possession without killing them, although how she does this is not currently known.
In book 7, the intentions of the Shadows are revealed. Apparently, the Shadows came from a planet that was "dying" (as stated by Trellis) and were intending to make Alledia their new home. They sent the Voice to help.