The first season of Demon Deviants premiered on June 7, 2009 and featured 10 episodes. The season follows a group of civilians and fighters must survive in a world of demons. As the demons taken over the world for 3 months. They must take down the demons' leader before he destroys the human race.
John, Cliff and the others rescue an unconscious Derek from the demon lair. Once Derek is awake, he is happily reunited with his family and learn that Derek is a half demon. John asks Derek if he can show them where he saw everything and he agrees. John, Cliff, Derek, Colonel Wright, Jesse and Jin leave to the demon lair but Jesse is captured. While looking for Jesse, they meet Tara. They find Jesse, unconscious on the floor. While being chased by demons, they stumble upon a ton of kids' bodies who are being transformed into demons. Demons try to barge into the room but John and the others escape through a window. Back at camp, Derek starts to hear voices in his head. The demons find their location and kill at least 40 people but Derek lifts them up in the air and throws them out of the camp. Derek then collapses onto the floor. Derek has a dream that a demon named Torchius is telling him to come back. Derek then bursts into flames and starts screaming in the dream. Lilly tells John that Derek seems to be developing powers and if he can't control them, he will kill everyone in the camp.
Derek then meets with Torchius and tells him that he needs to go with him but Derek rejects him until Torchius says he will kill his family and friends and Derek agrees to go with him. Along the way, Derek meets Colonel Wright's daughter, Dylan and John and Colonel Wright rescue Derek and Dylan. Torchius reveals the survivors have a traitor in the group and it is revealed to be Jesse. Jesse tries to kill Lilly but Derek shoots her in her shoulder. John takes a group (Derek, Cliff, Dylan, Nate and Jin) but are ambushed by a cult lead by a man named Damien, who are loyal to the demons. Colonel Wright takes a group (including Tara and Shawn) to find John and the others and they rescue them. John kills Damien. The survivors are struck with a plague, killing many of the survivors (including Shawn and Nelson). Tara is attacked by Jesse but is killed by Cliff. Torchius makes a deal, saying he will stop killing their people if Derek joins him and Derek agrees, and says his goodbye. John swears that he will get him back even if he has to go through Torchius.
Derek is learning how to use his powers by Torchius and John and Colonel Wright take Cliff, Tara and Dylan to rescue Derek. As soon as they arrive, Torchius kills Derek and John kills Torchius but they both heal. The survivors are being mind controlled by Torchius. John, Colonel Wright, Derek and Dylan go to find Torchius but run into his demons. They make it to Torchius' home, only to find him gone, They arrive home to find a little girl named April on the ground. Maria tries to warn John and Lilly about April but ignore her, Torchius reveals that April is a demon and they rush back to the camp. April attacks the survivors and is killed by Derek. Torchius then sends Abaddon to kill The Demon Resistance but John manages to kill Abaddon with the help of The Demon Resistance. The Demon Resistance and Torchius then battle, losing many of The Demon Resistance (including Nate). Derek kills Torchius but not before Torchius says that Derek will be like him someday. The Demon Resistance have won the battle but are separated from each other.
Ethan Hawke as John Mason- He was an author before the apocalypse. He escaped with his 3 sons and became close friends with Lilly and Scott. He is the second-in-command of the civilians and fighters. (10 episodes)
Olivia Wilde as Dr. Lilly Harper- She is the only doctor of the group. She cares about her patients alot and does everything she can to help out. She has become a very strong woman after she has lost everyone she ever loved. (9 episodes)
Devon Werkheiser as Cliff Mason- He is John's 18 year old son and oldest brother of Derek and Ben. He is one of the fighters for the group and cares deeply about his father and brother. He lost his mother during the apocalypse. He always looks out for his father when they are away from Derek and Cole. He is also Jesse's boyfriend. (10 episodes)
Cameron Bright as Derek Mason- John's 16 year old son and brother to Cole and Cliff. Derek develops powers when the demons attempted to make him a demon but only received the powers of mind reading, telepathy, strength, hearing and can communicates with demons. He got his intelligence from his father and is smarter than Cliff and Cole. He use to have asthma but due to his powers he no longer has asthma. He is a valuable member of the group and often fights along with his father and older brother. (10 episodes)
Dakota Goyo as Cole Mason- John's 9 year old son and younger brother to Cliff and Derek. Cole worries for his brothers and father's safety since they are always out fighting demons. He usually stays at the campsite and is babysat by Maria. (9 episodes)
Malese Jow as Tara- Tara is one of the fighters for the group. Tara hates the demons and takes her anger out on them. She is very brave, strong and a fighter. She joins the group in the first episode while out on her own when it came down. She was a runaway before the apocalypse and was weak. She came back to her foster home to save the children but found them dead. After being alone for 3 months she tried to commit suicide but could not bring herself to do it. After she attempted suicide she became much stronger. (10 episodes)
Thomas Jane as Colonel Scott Wright- Scott is the leader of the group. He was a colonel before the apocalypse and had a daughter and wife. His wife died when the apocalypse started and got separated from his daughter. He became close friends with John and made John his second-in-command. (10 episodes)
Ashley Benson as Jesse- Jesse is one of the fighters for the group and Cliff's girlfriend. Jesse cares a lot about Cliff and doesn't want anything to happen to him. Jesse is a tomboy and enjoys spending time with the guys. (4 episodes)
Christian Serratos as Maria Santos- Maria is Lilly's assistant. Maria cares deeply about Lilly and helps her out with her patients since she was trained by Lilly. Maria is religious and prays most of the time. She does not like the thought of demons being on earth and she avoids danger. (9 episodes)
Edwin Hodge as Nate- Nate is one of the fighters for the group. Nate was in the Army for a while until the apocalypse came down. Nate is close friends with John, Scott, Cliff and Jin. (10 episodes)
Rick Yune as Jin- Jin is one of the fighters for the group. Like Nate, he was in the Army for a while until the apocalypse came down. Jin has a thing for explosives. He is close friends with John, Cliff, Scott and Nate. (9 episodes)
Luke Benward as Shawn- Shawn is the youngest fighter of the group since he is only 14. Shawn disliked Derek at first but started to become friends with him. Shawn lost his parents during the apocalypse and hates demons for killing them. (5 episodes)
Connor Cruise as Nelson- Nelson is the same age as Shawn. Nelson wants to be a demon and worships them. He usually keeps to himself. (2 episodes)
Molly C. Quinn as Dylan Wright- Dylan is Colonel Wright's 16 year old daughter. She was separated from her father when the apocalypse came down but was found by Derek. She then becomes a fighter for the group. (9 episodes)
Doug Jones as Torchius- Torchius is the demon leader. (10 episodes)