Re: House Creation
Thought I'd throw out a few ideas for consideration:
Name: (Undecided - no real preference on that here. Offhand, I'd think something of a Greek origin would be ideal given that's the source of the Atreides name as well - going back to Atreus).
Banner & Arms: While the Atreides (who have led Caladan for centuries) maintained the hawk as their symbol with red, green and black as the color, I thought it would be a good touch (if not established prior to their rise) for the House to have a similar (ish) styling. Rather than a full hawk, I was thinking a bird's talon. That would denote their focus on more military strength than the bird as a whole. Color wise, they could maybe do Red, Black and Blue? Red and Black for the military backing and history and blue rather than green for the seas of Caladan. Similar, recognizable, but distinct enough that it would be distinguished from the former Atreides banner but still close enough to inspire the connection.
House Trait: With our primary Domain being Military with a Workers focus, I think Battle or Discipline would be the best route for the trait. Perhaps Battle (Strategy) or Discipline (Command, Composure or Precision). Any of those could convey a good positive quality towards the House and its main Domain focus, though which is probably a matter of the specific direction we'd want to go with the House. Strategy? They'd be viewed as Strategic masterminds in the Empire, so someone who could step into the shoes of the Atreides quite easily in whatever aims they held before their demise. Discipline (all three) could convey the House as extremely level headed and deliberate. They won't act hastily, so provoking them would be hard - but when they strike, it'd be with laser focus. Two options at least!
History: As for the history of the House... the primary vote gives a good bit I think. The House is located close to Castle Caladan and the seat of the Atreides' power. They were in charge (most recently at least) of training its military forces and logistics personnel. Something like that doesn't happen overnight, so it'd make sense that they've been present and slowly mastering their skills for a couple centuries at least. The Dukes had entrusted this House with the training and equipment necessary to recruit and educate their armies, so they stood in some favor. They'd have had dealings with others around the Imperium to a point, likely training select people (by contract and most likely with the Atreides permission).
Lot of potential there for miscellaneous historical events that could have denoted the recruitment or rise of any of our players along the way too as advisors, counselors, envoys, Masters, etc.