Changing Circumstances (http://archiveofourown.org/works/1151147/chapters/2333621) by EclipseWing
Summary: Post 7.17 The Born Again Identity As a reward from God (who may or may not be drunk) Team Free Will (and those reluctantly dragged along) end up attending Hogwarts School of Witchcraft and Wizardry. Madness ensures. (In which Dean and Meg have a weird fascination with Hell, Crowley starts an underground black market, Gabriel has it out for Snape, Sam makes a female friend who doesn't die, Castiel watches Lord of the Rings, Adam gets out of the cage and Jo is the only sane one around.)
I think this is what you're looking for, it almost fits what you're describing. Except Jimmy wasn't in it and Michael and Lucifer were still in the cage.
no subject
Summary:
Post 7.17 The Born Again Identity
As a reward from God (who may or may not be drunk) Team Free Will (and those reluctantly dragged along) end up attending Hogwarts School of Witchcraft and Wizardry.
Madness ensures.
(In which Dean and Meg have a weird fascination with Hell, Crowley starts an underground black market, Gabriel has it out for Snape, Sam makes a female friend who doesn't die, Castiel watches Lord of the Rings, Adam gets out of the cage and Jo is the only sane one around.)
I think this is what you're looking for, it almost fits what you're describing. Except Jimmy wasn't in it and Michael and Lucifer were still in the cage.