This has been in the back of my head for a while now.
Season 6 SPN had plots about hunting down weapons from Heaven. Between that and a fic I have been following lately, I had an interesting thought:
The Allspark and the Matrix were weapons from Heaven.
They were left on a dead rock of a planet somewhere the other side of the universe because they were far too dangerous to keep on Earth, but even on a dead rock, they were still working... and Cybertronians were born.
So some time after they end up on Earth, angels decide to retrieve them.
The timing is a bit iffy, the first movie is probably somewhere in 3rd season SPN and angels are not yet on Earth, but the Matrix is on Earth around the same time as when the angelic civil war (season 6) is happening, so maybe an interesting story could be made of attempts to get a hold of it by both sides).
The Winchester brothers get involved because their angel friend, Castiel, is the leader of one side of the Heavenly civil war.
(Cross-posted to
spn_bunnies.