Apparenttly, many years ago, Daud was Corvo, he must have drawn the Outsider's attention somehow; he was a guy who felt good about being able to "change things" (and "being important"), it was probably something that made the Outsider gift him.
Forward 10 years or more, the Outsider doesn't talk to Daud anymore ("it's been a long time, but you've got my attention again") and when he finally does, he sounds somehow disappointed and... irritated (?). He grants his powers to the guy he knows will pursue Daud for what he did. He orchestrates this.
What happened? Did Daud just go bad, arrogant and drunk on his new powers? Or was the Whaler gang his idea of "changing things"? Did the Ousider just get bored and left, which caused Daud to become disillusioned about this "greater purpose" that he imagined he had?
Really interesting. I feel like we're only scratching the surface of Daud. Thoughts?