Two brothers follow their father's footsteps as hunters, fighting evil supernatural beings of many kinds, including monsters, demons, and gods that roam the earth.
The character of Bobby Singer was originally supposed to be named Bobby Manners, after Robert Singer and Kim Manners, who had both greatly contributed to the show. However, after discovering that there was an actual Bobby Manners, the character's last name was changed to Singer.
Dean Winchester:
I like him, he says okie dokie.
The show's rules say that the biggest flag for demonic possession is sulfur. We often see Sam and Dean sniff for it, or sniff a yellow powder suspected to be sulfur. Pure sulfur actually doesn't have the rotten-egg odor we associate with it - that's hydrogen sulfide, which is a gas. Pure sulfur is odorless.
The opening credits are shown during an early scene.
English