Vermine were creatures that travelled from another dimension using red light, and possessed anything that was red. They entered N-Space via Bevell's shop in a jigsaw piece. They wanted to invade and conquer the universe. The Ninth Doctor trapped them in a mirrored music box. (AUDIO: The Colour of Terror [+]Lizzie Hopley, Shades of Fear (The Ninth Doctor Adventures: Series 2, Big Finish Productions, 2023).)
Some of the Vermine escaped through time and merged with the Vashta Nerada to create the Red Darkness. (AUDIO: Red Darkness [+]Roy Gill, Shades of Fear (The Ninth Doctor Adventures: Series 2, Big Finish Productions, 2023).)