How about, say, old yellow-eyes isn't a demon but a terminator? We all know there are red-eyed ones and blue-eyed ones; well, this is a different model, a yellow-eyed one.

Possibly the time travel thing was fucked up, it came back to kill Sam and/or Mary, but was interrupted. Because Sam is the boy king at the end of the world, rite? Just like John Connor.

Anywayz, the Colt is a spesh electrocution gun. In about 15 years Dean is going to go back in time and build it, piece by piece.

Mal = Xena
River = Callisto
Jayne = Gabrielle
Simon = Joxer
Zoe = Ares
Kaylee = Aphrodite

in the midst of watching return of the king, i'm struck by the following:

in the first half of the film at least, it's totally
frodo = simon
sam = jayne
gollum = river.

TOTES. that look gollum gives sam after the whole "i am on your side, mister frodo!" and frodo takes gollum's hand? TOTALLY the look river gives jayne after simon is all doctory in ariel hospital. bwee ot3cakes.

alternatively, you could look at the sibling dynamic with
river = boromir
simon = faramir
where river comes back broken and simon's left all sad and responsible and never-quite-as-good-as-her. yep.

or fellowshippy - mal is totes aragorn/strider (no explanation necessary). and legolas and gimli? zoe and wash.