In Which I Have A Theory About Supernatural Season Seven…
The Talmud Baba Batra 75b states that the archangels Michael and Gabriel will be the ones who slay the Leviathan.
Remember in 07x01 when God!Leviathan!Whatever!Cas went to force Crowley into work for him, he said specifically that it was because he needed a threat to hold over his enemies and “we need to keep Michael in Lucifer’s cage.” What if the “we” isn’t Cas and Crowley, but the Leviathans? We have already seen that they were able to influence Cas and take full control of him for brief periods of time.
Gabriel and Michael!Adam could full on save the day, but most importantly bring Cas back! It would also free Adam from the cage as an added bonus.
Remember in 07x01 when God!Leviathan!Whatever!Cas went to force Crowley into work for him, he said specifically that it was because he needed a threat to hold over his enemies and “we need to keep Michael in Lucifer’s cage.” What if the “we” isn’t Cas and Crowley, but the Leviathans? We have already seen that they were able to influence Cas and take full control of him for brief periods of time.
Gabriel and Michael!Adam could full on save the day, but most importantly bring Cas back! It would also free Adam from the cage as an added bonus.