These are my thoughts on General Hiraga, mostly dealing with Earth Flight, but also including a line from Sol 2781.
“’But the dining hall was full of special guests here for the ceremony, including the terrifying General Hiraga herself!'” Earth Flight, pg 184
Which raises the question of why General Hiraga was at Zulu base for the ceremony. She can't reasonably be there to manage the base temporarily, because even if Riak Torrek was caught up in the ceremonies, Leveque and Stone are both very competent and actually work there. Which suggests that General Hiraga had to be involved in the ceremony itself. Could she be using the ceremony as a cover to covertly talk with Dragon or Riak? Possibly, but the Military has secure communications, and the chimera haven't been rediscovered yet, so that seems unlikely. She could be there to scare disobedient officers into submission, but Dragon can do that too.
Now who could be considered a special guest? Tell Clan members, Military alliance members, Fian's mom, Jarra's friends and ProMum, even the representatives from the gentes maiores clans assuming they got there early. There was a big audience, and I might be missing some obvious category, but members of the general audience would not be special enough to merit accommodation on Zulu base. The August clan and their alliance got to Zulu base too late for them to be her reason for attending.
Now here's a quote from Sol:
"The one exception being that the terrifying General Hiraga had declined the honour when she was appointed to be the head of Planet First Command, immediately making it known that she regarded the use of her first name as being a presumptuous act of overfamiliarity. Actually, nobody seemed to know General Hiraga’s first name anyway. She appeared to have been on record as just Hiraga since her first day at Military school.” Sol 2781, 168
This suggests that General Hiraga is extremely private about her personal life and history, while also proposing that she grew up in a Military family.
Potentially, she had some breech with her family or maybe its a cover story, with details backdated on Military records or something. We don't know, but there's likely something interesting going on. It also raises the question of whether or not there are other terrifying Hiragas in the Military. For the sake of this post, I'm assuming she actually has a Military family, which would eliminate many other reasons for being at the ceremony, like a connection to Fian's mother.
So General Hiraga was a special guest at Jarra's clan presentation and betrothal ceremony. Most of the special guests are connected to a Betan clan, so General Hiraga probably is too. She doesn't have an obvious clan prefix in her name, so the options I see are:
She's married to someone in the Tell clan (unusual naming rules).
She's married to a Betan in a different clan where clan members by adoption don't take the clan prefix, or one that's the "Hir" or "Aga" clan.
She's in a situation like Ursula, split between clans.
She's married to a Betan in a clan where clan members by adoption take the clan prefix, but she's chosen not to because she's extremely private about her personal life.
Where the clan isn't the Tell clan, it would have to be a Military alliance clan (more likely) or a gentes maiores clan.
Really, my theories about General Hiraga come down to the fact that she could be a member of the Tell clan by marriage. Probably not because Drago would be less terrified of her, but the possibility was there. Maybe I'm missing something, but I suspect she has an interesting backstory.
