 They are minor villains in the series who have appeared twice so far.They first appeared in series two when they helped Dr. Klench on the agreement that Klench would help let their race survive, and then in series three the Infernons helped a history lecturer destroy the past so there was less to teach.The Infernons appear to know little about how the human body works, as is evidenced by Nebulous tricking them into thinking they live via photosynthesis.