Chivalry’s pretensions of being almost--but not quite--royal don’t come out of nowhere; she is a granddaughter of someone in the line of succession for the Altamaian throne (which is currently under the control of the Hyperians but they are USURPERS and Chivalry’s grown up hearing about it) and has the royal surname as part of her name as a kind of courtesy title because of that.
Now, she shares those circumstances with about 1,200 other living people, because that’s how asexual colony-breeding species Work, BUT her adoptive parents (which for astraeas = the family you are legally in the hereditary lineage of because they’re 95% sterile and EVERYONE is adopted) are a Fortefemen raised in a different noble family AND a second daughter of the Vega clan, which can trace its lineage back to the original landings on Altamai (as can the Revoni clan, who are their historic allies and traditionally marry every subsequent generation of oldest adoptive daughters to each other), so she’s close to the throne by marriage and adoption which are the only ways astraeas get close to anything.
Noble titles get passed back and forth in alternating generations from the colony’s Mother to the First Daughter (as in literally the first child the Mother bears in her life) who then has the duty of raising the colony’s next Mother when she is born. That Mother then inherits the title from her aunt and the cycle repeats.
Being a second daughter generally entails being adopted into the title-bearing household but not inheriting the title or ancestral land. You’re still probably set for life--titles being passed through Mothers theoretically ensures that the property is the recourse of the colony, but as royal favor and nobles being representatives of their colonies at court has become more and more important that’s become much more of a trickle-down effect to the point where you can have a royal name but be living a peasant’s lifestyle on the dregs. Generally the closer you are to the Mother and/or First Daughter the better off you’ll be.
As the youngest adoptive child of a second daughter, Chivalry kind of gets all the perks and none of the responsibility--she’s not expected to marry any particular ally or raise any particular scionette--and she’s secretly pretty down with that, she kind of just thinks her beef with the empire tastes better when it’s personal