1. The Scions
The Scions, specifically, are the first-generation children of Dominus and his empress Olyssia Zin. One, Azrion, served as an emperor himself, and each one is also associated with a Vigilant Virtue.
They include:
Azrion the Conqueror (the firstborn son of Dominus)
Tristan the Valiant (patron saint of the Sword-Maidens)
Bronos the Just (the brother whom the rest turned to for a fair hearing)
Galen the Adept (helped found the Royal Collegium)
Evindra the Righteous (longest-lived of the Scions)
Korol the Devout (whose writings form much of the Vigilant Codex)
All Luminai who fit the genetic profile look more or less like Vaelen, seen in Deradune, though their appearance is on a spectrum of course. The highborn Cassians are now too distant from that heritage (due to the Ancestral Decree) to show such strong physical features.
Source: Reddit2. About Chaul, the Ghost House
In a way, Chaul the Scion has gotten a bad rap through know fault of his own - Chaul is known as the ghost house because it was the house of emperor Vorios the False, the disgraced usurper slain by the current emperor, Myrcalus, to attain the throne. House Chaul's treachery was so thorough that all traces and references to him and his house were removed. That was inspired in part by the fate of Hatshepsut in ancient Egypt.
3. What virtue did Chaul represent before he was unpersoned
Not saying he was, not saying he wasn't. We haven't told his story yet. ;) But the guy who ran his house was such a jerk it got the whole house wiped from the history books. Which virtue? Well, these shattered datachrons and burned documents are awfully hard to read, so I can't say for sure. But if I had to guess, I'd say something like cunning. But like I said, the datachrons are shattered. If Pappy has one that's in better shape and gives a different answer, go with that one.