[Warr's note: until I work out a Homebrew alternative, this faction could pull double duty as a de-facto Highborn origin]
You have a claim to one of these lineages, though likely as a footnote in the roots of some tall family tree. You may be envious of those who sit far above you, this bitterness you harbour spurring you on — are you willing to do what is takes to climb up to the next branch? You may have decided to begin building your own base of power in the Emperor’s service, to make yourself legitimate in your own right. You may have served time in the Imperial Navy Navy or Astra Militarum, becoming accustomed to working on voidships or fighting on the frontlines, or you may have become embroiled in political machinations, gathering power and knowledge from serving in the Administratum. Though you have suffered greatly and likely lacked even the meagre privileges you were born to, all of this effort has been towards the higher purpose of securing a destiny of your own.
For now you remain fettered to your Dynasty, obliged to act according to your Highborn status and fulfil your duties. Those above you ask for countless favours that you cannot deny. You might have spent some time running about the galaxy delivering precious freight, perhaps smuggling a few things for yourself on the side. If you served with the Astra Militarum or Navis Imperialis you may have been ordered to lead a pitifully small cadre of troops into combat, risking your own life so that the family crest could be seen on the front lines. Your Dynasty has found a use for you one way or another, as otherwise you’d just be another spoilt highborn mouth to feed.
Then, a new Patron appears and offers you even more opportunities for personal gain, setting the stage for the next chapter of your legacy. They might think they’re getting the better end of the deal, but you have to make sure that’s not the case: maybe you can take a cut of their business for yourself or perhaps you work for them to repay your Dynasty’s debt, gaining favour from both camps? In the end, the balance of this arrangement should favour yourself and your Dynasty, either to rebuild a fallen house, or to forge the foundations for a new one.