As Supernatural rolls towards the impressive landmark of a thirteenth season, thoughts inevitably turn to where the crazy life of Sam and Dean Winchester will end up next and, perhaps more importantly, who'll be rearing their ugly head in an attempt to bring about the apocalypse next season. Interestingly, executive producer Andrew Dabb recently stated that season 13's main villain would be someone fans are familiar with, triggering speculation as to who this mysterious character might be.
Dabb claimed that Lucifer's newborn (yet somehow teenage) son Jack is, shockingly, not the biggest worry on the Winchesters' minds in the forthcoming season and that an "old friend we have not seen for many years" would be the primary threat this time around.
Of course, in the season 12 finale, a post-apocalyptic alternate reality was introduced in which the Winchester brothers were never born and this gives the show scope to both revive dead villains and introduce evil versions of characters that are virtuous in the main world. Alternatively, the new enemy could simply be a character that gets revived, released or is otherwise returned to wreak havoc upon the world/midwest U.S.A. Nothing is ever straightforward in the world of Supernatural but here are some of the prime candidates for this "old friend" who will be the chief Winchester-troubler in season 13.
Poor Michael. And poor Adam, too. As much as Sam and Dean harp on about the importance of family, it's worth remembering that they currently have a half-brother stuck inside The Cage with a mad archangel using him as a vessel. Michael certainly fits the criteria of a character who hasn't been seen for years and has been conspicuous by his absence in recent seasons, with only the odd passing comment about the archangel's damaged state of mind for fans to go on.
Michael and Adam would certainly bear a grudge, having been driven insane and abandoned by angels and Winchesters alike and as an archangel, Michael would offer a viable and substantial threat. Additionally, with Lucifer's son now unleashed upon the world and the big man downstairs himself still not completely out of the picture, it makes sense that Michael may finally venture out from his prison to unleash merry hell. It's also likely that should Michael return, he'll no longer be on any one side, with the disintegration of his mental state making him an unpredictable and chaotic enemy, rather than a scheming, tyrannical one.
Such a plot would finally give Supernatural a chance to tie up the Adam story line, as it still feels as if he and the Winchesters have unfinished business, particularly if Mary returns to fray. It'll be interesting to see how Mama Winchester reacts to her husband's other child.
Sometimes the originals are the best. Arguably Supernatural's first arch villain, Azazel was killed at the hands of a Colt-wielding Dean Winchester, who finally managed to get some measure of vengeance for the horrors his family endured. However, with a new alternate reality in play, a different version of Azazel could come to the fore. Although the villain might be a step down in terms of power, his status as the show's first big villain and his immensely personal connection to the Winchester family ensures that his presence in season 13 would be just as dramatic and suspenseful as any other villain's might be.
It has already been established that although Mary never made a deal with Azazel in the other world, the Prince of Hell did manage to kill both Mary and John on different occasions. Furthermore, with Lucifer now in the alternate universe and Azazel being one of his most loyal followers, it's impossible to not rule out a team-up between the main world's Devil and the alternate world's Prince of Hell.
If the demon known as "Yellow Eyes" could somehow find his way to the main world, he'd surely be delighted at the prospect of extra Winchesters to kill, as well as the attraction of a whole new universe that hasn't been ravaged by the apocalypse to invade. Azazel may even conspire to escape the demons' battle against the angels by opening a portal to Sam and Dean's world. That certainly sounds like a season's worth of bother.