"Nope. They're tainted, but not from the Fade and they don't draw upon it. Demons try to possess people, especially mages. Darkspawn can't do that. Those of them that can use magic don't draw upon the Fade at all, but their taint somehow. You'd have to ask a Grey Warden for specifics; that's the order dedicated to fighting them and stopping the Blights. Blights are when darkspawn unearth an archdemon, a tainted version of the Old Gods, and it leads them to the surface to take it over. When that happens, the land and sky suffer as well as the people. The Grey Wardens show up, kill the archdemon, and they scatter. Job done, until next time. There have been five Blights throughout history, one happening just a decade ago. If legend is right, we have two more to go.

And before you ask, I didn't see the Fifth Blight happen. I wasn't in Ferelden when it happened, and it thankfully didn't have a chance to spread beyond."