He spoke with Entertainment Weekly recently about how his idea morphed from being a horror show about reporter who followed urban legend leads around the country to being about two brothers who did the same.
After their mother’s horrific Yellow-Eyed Demon death, Sam and Dean traveled with their hunter father, and were trained to hunt one day.
If you think the differences stopped there, consider this: Kripke was going to have Dean be the only brother who knew about the supernatural when they were kids. I. KNOW!
But, Supernatural’s creator, Eric Kripke, originally had a very different idea in mind when he started thinking about the series and took his first few stabs at the pilot.