I HAS A THEORY
After reading assorted fics, as well as 'Good Omens' (which is totally awesome), I have come up with the following crack theory:
The Trickster isn't exactly a demigod as such. I think he seems quite similar to Crowley, at least powers-wise. The demonic/angelic powers displayed in 'Good Omens' are reminiscent of the Trickster's. Crowley tends to make things by sheer will, as does the Trickster, and bring animals/people back to life. OBVSLY the Trickster is in fact a [fallen?] angel who took on the guise of a trickster to smote those deserving. Demigod, angel, powers are similar, the name doesn't matter.
And to carry it even further, the Trickster is actually the one who has Dean's contract, and wants to make him his apprentice (because he's so awesome!), which is why he told Sam to stop trying to save Dean. Hell is a codeword for "awesome place full of cake and pretty womens".
Fuck, I oughta write this fic! :D