If you could change any plot lines or story arcs what would you want to change?
shareFor season 12, Mary wouldn't have come back and there would have been no BMOL.
For season 8, Sam would have looked for Dean. Whether he failed or succeeded in finding him would have been irrelevant, but he would have looked.
I'd have had Demon Dean storyline last longer and been more exciting and suspenseful. Jensen was born to play the badass. Best scene ever was Dean walking through the red-lit corridors of the bunker carrying a hammer and yelling "Sammy".
We also could have been witness to Dean's good/evil struggles as MOC Dean. They never really gave that storyline a chance either.