Dave of Canada wrote...
On Thedas, there's no true "undead" and everything we've seen such as corpses and ghosts are usually demons or spirits taking one shape or another. Reading the codex entry for Corpses, you'd learn they are simply demons who've entered the bodies of the deceased.
However, for the demon to enter inside the dead body, the body would require a connection to the Fade.
I think there are two other ways which don't require a connection to the Fade: demon summoning by mages (maleficar is implied by the codex), and Veil tears.
So assuming they'd need a passage which would allow them to slip inside their awaiting host, what would occur if the body belonged to somebody tranquil? Could demons "see" the body in the Fade? Would blood mages be capable of "rising" the corpse?
How about non-tranquil corpses? Assuming the tranquil corpses are invisible to demons, could people hypothetically tranquil their deceased friends / comrades / family so their bodies cannot be possessed or must the ritual be performed on a live host?
Thoughts on the subject?
The way I see it, demons seem to consider what they'd gain by possessing creatures. Emotions and power seem likely. But what would a demon get out of possessing a dead body? This one is unclear. So I assume that the blood mage is forcing the demon into someone's body, in that the mage is controlling the demon.
(Of course, there is the matter of spirits/demons entering trees as well, which has me somewhat flummoxed, I must admit. So, maybe it is something beyond mere emotions or power, maybe it is that those spirits/demons having crossed over cannot survive for long in that form or that their urge for experiencing life is so great that they don't mind possessing "any" creature.)
Now as to what would happen with Veil tears, when a mage is absent: I suppose we might also think of it as memories seemingly lingering on inside the body even when the soul has vacated it. This might attract demons who might cross over through the tear.
As to performing the Rite of Tranquility on dead bodies... it seems to me on initial thought to be a crazy idea...

What might attract demons across the Fade is that the soul/spirit of the living is visible to them, but once the spirits/demons cross over, it's anyone's guess if even Tranquil (living or dead) are not susceptible to being possessed.