Unrelated: We need an Ishgardian GC, preferably the Temple Knights. Be awesome serving under Aymeric and Lucia.

Related to your post:

I would have to go with the Eternal Flames RP-wise for a few reasons.

1. The wealthy Syndicate of Ul'dah and their Brass Blades often see themselves as being above the law and act like bullies, since their employers have power many of them get away with it. Given the nature of the Drk's mission to punish those that think themselves above the law, that makes the most sense to me as the Flames and the Blades don't always act with unity and fight at various points.

2. Raubahn is the commander of the Flames. A proud and powerful warrior that has an inner darkness all his own that you see him unleash. A Drk could most likely respect, sympathize, and understand having to cope with something of that nature.

3. There are several wealthy folks in general in Ul'dah that have no issue with exploiting the poor and downtrodden and not just the members of the syndicate, you learn in various class missions that there are some criminal organizations working. While a drk won't face them in their class story per se, it once more squares quite well with their mission of punishing others that think themselves beyond the law, while this seems to mostly include those that are in power and abusing it, I could easily see that also applying by extension to any sort of organization that grows too strong and abuses the people.

Ul'dah is a fairly corrupt nation in a lot of places, I feel the Drk's special sort of policing fits in perfectly with their overall lore/theme.