That deals with Corvo before the start of the game. It would be great to have 2-3 missions that lead up to Corvo being sent off to the other islands looking for help. This would give a chance to help flesh out the Empresses character a bit to give more reason to actually care about the fact that she died. It doesn't need to be big just a couple missions just to flesh out the Empress and her relationship with Corvo.

Steady on! They haven't even released the second DLC pack yet.

I agree that the relationship between Corvo and the Empress wasn't fleshed out well, but that doesn't mean we need more missions controlling Corvo: there are plenty other ways Arkane can develop the Empress' character.

This would also have to be a DLC without any outsider powers. Not saying that's undoable, but just something to keep in mind.

Corvo had an entire game, Daud's cooler anyhow.

yes which is why I mentioned it only being 2-3 missions. Long enough to get a feel for the relationship between the empress and Corvo but short enough that it can be done quickly and get on to the meat of the game.