Dan, Cassidy was hired to handle the special effects on a Movie called the Blue Devil. He created an outfit for the character of the Blue Devil. The kevlar costume was not only strong but it was made to be flexible so it could handle rigorous stunts. It was powered by miniature servo motors to add strength.

During the shooting the Blue Devil suit performed perfectly. Unfortunately and coincidentally a daemon named Nebiros interrupted the shooting of the film. While fighting the Blue Devil Nebiros, assumed he was a fellow demon. So when the fight starts going bad for Nebriros he zaps the Blue Devil with a blast intended to drain his occult energy.

When the battle is over Dan Cassidy finds that his suit is a part of him. He discovers that the suit is organic and part of his body. Dan Cassidy is very upset about what has happened to him but because of his powers he ends up being a reluctant hero. He tries many ways and uses the help of many people but he is never able to remove his suit.

The Blue Devil continues to be a hero for years he even joins the Justice League America for a while. He would eventually be killed by mist along with a few other hero. He is killed by holy water placed in the sprinkler system. Because the Blue Devil is part daemon he is reduced to bare bones. He would later be resurrected by Faust. Blue Devil would later work with the super hero team of magic users the Shadowpact. He has recently left the team in place of Zauriel who atacked him under orders due to Blue Devil's popularity causing humans to make deals like his. He is currently attempting to fix the problem on his own. The blast by Nebiros in the original battle aside from fusing the suit to Dan Also changed the trident that was part of the costume.Prior to the battle it was a simple flame thrower with some pirotechnicks after the battle it has become a powerful magic device linked to the netherworlds. When the gateway between Earth and the netherworlds is open it is at its most formidable making the bearer a match for a legion of demons. It is thought controlled and answers to the mind of either Dan Cassidy or Nebiros. If iether holds it they are dominant lord when not in physical contact it can become a battle of wills for controll so far Dan has always been the victor.
  During the Infinite Crisis, the Blue Devil was the bouncer for the Oblivion Bar. When Enchantress tried to ask people to join her a fight the Spectre, he comes and tells her its suicide to do something like that. He goes with the rest of Shadowpact to fight Eclipso. He tries to send her to hell with his trident but she makes the comment that she isnt from hell. He then is thrown blocks away by a back slap by Eclipso. He comes back and asks Enchantress what is she doing being in the same spot since the fight started. She tells him that she is tapping into the energy that Captain Marvel gets his power from and is giving her own powers to him. He then asks her if she could tap into everyone in teh world with magic and so she does. He then grabs his trident and throws it into Eclipso which leaves her on the ground with dark energy leaking from her. Blue Devil punches Enchantress when she turns evil knocking her out.