User blog comment:DarkIngRidley/What ''old friend'' do you think is gonna appear in Season Seven, Episode Twelve??/@comment-3481504-20120102214323

I don't think it's going to be Castiel, going off the premise that he'll only reappear in the seventeenth episode (and maybe again after that), which is what I heard. And it definitely won't be Lucifer, as the writers concluded that he wouldn't leave the fifth season, minus the whole hallucination deal.