Reanimation is how that works, magic gets involved. Necromancy, not demons. Some of them were buried as they were, withered into what they became with some little life in them since they—it's not sleep but close, rest? -- and rise when disturbed or at night even in their deep burial mounds. Some of the draugr can speak, just fragments, old things. Old as them and the days when they walked the world.

[Some shout. Not a thing to say.]

The skeletons wear their old weapons too though, the wind sighs in their bones as time does, walking until you stop it with an arrow. The new ones are only through necromancy though, more reason that it's—

[Allowed here but listen to it catch like a fishhook in her mouth, how distasteful a word it is; the dead risen, hurling themselves at you to fall to ash when their time is spent.]