He may deal with demons and other creatures that go bump in the night on "Supernatural," and now creator Eric Kripke has sold his soul to Warner Bros. television ... at least for two years. Although the terms of the deal state that Kripke will continue to executive produce the paranormal series, that doesn't mean "Supernatural" is entirely safe. The terms of the deal also have Kripke developing new projects for the Warner Bros. brand. However, there is an interesting notion that one of these new projects will turn out to be a prequel to "Supernatural" set in the era of the old west, revolving around the show's mythology. The agreement itself is similar to one that is currently in play at Fox with actress Eliza Dusku (currently developing "Dollhouse" with former "Buffy The Vampire Slayer creator, Joss Whedon) and at The CW with Justin Hartley who will be reprising his Green Arrow role on "Smallville." "Supernatural" returns for its fourth season in the fall.