Dan Cassidy was working as a stuntman and special effects specialist in Hollywood when he created the Blue Devil full body suit, complete with a built in exoskeleton, specifically designed for the Blue Devil movie being produced by Verner Brothers Studios.
During filming on île du Diable, the demon Nebiros was accidentally unleashed from within an ancient temple and, thinking Cassidy was an actual demon, tried to drain his demonic powers with blasts of magic. Instead, the blasts permanently bonded the suit to Cassidy. This unnatural fusion of magic and technology caused Cassidy to experience unusual events and draw the attention of otherworldly beings, a condition known in occult circles as a "weirdness magnet".
Horrified at the prospect of being stuck in the suit forever, Cassidy sought ways to separate himself from it, becoming a reluctant super hero along the way.