Someone asked about how much creative control Jared and Jensen have over the show’s story line, and Jensen said none. He said he could probably give feedback that would help shape the story somewhat, but that’s the writers’ domain. They’re also so far ahead of where filming is – they’re breaking the last episode now and the actors are filming episode 15.
Jensen: The character is a collaboration between the writers and what I do with it. Eric Kripke incorporated nuances of what we did from the beginning, like Dean eating so much.
He said that the writers do defer to Jared and Jensen now when there are character issues, since they’re the ones who have lived with them. The writers know how much they want to protect the integrity of those characters.