Corvo's relation to Daud is intentional, as Bare says his character arc is the direct opposite of the Dishonored hero. "Daud is coming in with more backstory than Corvo," Bare said. "He's got a past as a very brutal assassin. Corvo started with more of a clean slate and he could have turned dark; Daud is sort of the inverse." Daud's path started very dark, Bare says, and he can continue down it or "turn a corner."
That means that the DLC, like the original game, will have two very distinct endings based on High and Low Chaos, with minor variations based on how you perform in missions. Given how easy and exhilarating it was to fall into using Daud's tools for their natural (brutal) purposes, I imagine many players will be making Dunwall extremely chaotic.
Dishonored 'The Knife of Dunwall'