Honestly what needs more filling in is the Fire Mandrills early history.
It's always been implied (to me anyway) that the Clan wasn't half bad in the early days. The Kindred Associations or Kindrasc started as a kind of competitiveness to demonstrate their own prowess, and the prowess of their bloodline, an early manifestation of the eugenics program actually shaping the behavior and goals of individual warriors. It was also individual warriors and eventually Bloodname Houses pooling some resources together as allies.
I've always found the Clans Bloodname House politics interesting. And some version of that being told could be an interesting variation on Bloodname House politics. Just taken to a unique place.
There also used to be a lot more Kindraa that we don't have names or information for. Originally 14 of them. Over the decades Clan fans have been eager to learn more about the Clans that were already gone, like Widowmaker and Mongoose. I definitely think there could be some interesting stories to tell about some of the Kindraa that we never got a chance to know.
We also have an exclusive bloodname, Jannik, that never gets a single named reference anywhere. I suspect by the 3050s this is a subordinate Bloodname House to another Kindraa, like Sainze, where all the senior officers tend to be of the leading Bloodname House(s) of that Kindraa and so all the Jannik warriors are subordinates. But it also just leaves room to flesh out that Bloodname, its history, characteristics, etc.
There are some story worthy gaps here for sure, IMO. But I do think it's mostly to be found in the early days of the Clans, or the Golden Century. For the Mandrills those eras probably represented a more hopeful and optimistic time. The closest thing the Mandrills ever had to a golden age.
Feel free to use any of the above for inspiration for story writing.
