Welp, not exactly one NPC, but I will still ask. What do you think happened with House Thul and their leader on Alderaan
Thank you for asking me this! Sorry it took me awhile to get to it!
I have several head-canons already. But here's the quick breakdown:
Lord Jorad Sindarus Thul (the rather inept, passive leader of House Thul during the Empire-side world missions) and a significant chunk of House Thul's leadership are killed during the Zakuulan invasion. Although Thul is cut off from the Empire's support, the same can be said for Organa and the Republic. As we see in the Star Fortress mission to Alderaan, the situation there is bad and stagnant, with a lack of organization.
Once the Star Fortress - and the threat of Zakuul - are removed, things start to change.
The Alliance negotiates a deal with Acina that the Empire will suspend support to Thul. (The condition being that they'll also keep Organa from rearming through the Republic.)
The Alliance then begins a number of relief missions to Alderaan, helping to stabilize the political situation.
Eventually, and it takes a few years, the Alliance essentially plays "kingmaker" - first for House Thul, then later for the actual throne of Alderaan itself.
Enter Duke Horis Thul.
Horis Thul remembers Corellan well; after all, Corellan saved the Duke from Aleyna Hark years before during the Desolator crisis. He was already agreeable to peace negotiations; only the Zakuulan subjugation held up the process.
It takes a LOT of work, with Ulannium Kaarz and Vector Hyllus doing much of the negotiations. But eventually, Horis is one of the signatories of a new Treaty of Alderaan, bringing decades of civil war to a close. (Naturally, House Thul's exile is officially ended by this treaty.)
Thank you for the ask!