Enslaved at the young age of 357 years, Erdhig served a decent enough life style for a smaller house in the lower kingdoms near the base of the CloudSpires range until he was enslaved during a raid while transporting gold stock.
A native of Urqzat, he is a trained mathematician who was in the wrong place at the wrong time and resultantly found himself traded from one merchant to the next.
He does not seem to mind the life style, as he is personally not associated with anyone and has committed no crime to end up where he is; possibly he prefers it to what he had in the service to whatever house.
In truth, if asked, he simply responds that life seems to be providing him with adventure despite his best effort to lead a boring and safe life.
As far as duergar go, he is still a Lawful Evil individual, who has traditionally placed his loyalty in whom he deems best for his interests. His interests mostly involve staying alive, given nearly every environment he's been traded to in the last fifty years has been hostile or contested territory where he's been responsible for adding and tracking the phat lootz whatever organization that bought him has been obtaining.