In the aftermath, the new Khan dials back the Clan's hyper aggressive, overly confrontational and war crime-y style of conflict. They're still aggressive and not seen in a particularly good light but they haven't embarked into any deep feuds or grandstanding yet.
Part of this effort, is reconfiguring the sibkos to gradually increase numbers per sibko each year until they double by 2855. Also as candidates test out, they get passed to "remedial" sibkos which attempt to salvage candidates before a second testing out occurs. Those who succeed from this "second chance" by passing a trial of position become simple warriors in second line formations. Trueborns that make it through this route aren't exactly denied Bloodnames but their route is typically only through a grand melee as sponsors heavily favor those who did not fail the first time. Lastly, a potential recruit is only given an initial trial of position against two targets, allowing them only a chance of being a warrior or star commander and if successful are assigned to a 2 year seasoning tour in a cadre cluster before being assigned to a combat cluster (front or second-line) or forcing a second trial of position for higher rank.
Freeborns by comparison aren't exactly as disregarded as some Clans and can rise to Cluster command but Galaxy Command requires a Bloodname or significant batte honors as determined by Clan Mongoose's Loremaster. However it is only the best Freeborns who make it to front-line combat clusters, most ending up in second-line formations.
If a warrior survives to 40 without earning a Bloodname or achieving some noteworthy battle honors, they are typically reassigned to a solahma cluster. If still capable or retirement to a lower caste.The Mongoose practice a mandatory retirement at age 75 regardless of caste where they serve a partial social role in the early care of young sibkos, and uncharacteristically for most Clans allowing a degree of independence in activity and relaxation in their final years. Should a Mongoose enter a terminal decline, they often choose to quietly end their lives and if unable to do so, a scientist committee may intervene and employ euthanasia.
Beyond that, the immediate military reforms are mostly minor at first. He'll direct the scientists towards a Clan version of the Dart II Light Artillery Missile (outlined previously in one of my older AU posts), the canonical Targeting Computer and what for now is being called Modular Internal Structure (increases the weight of IS to 12% instead of 10%, takes up 7 crit locations (mech) or lowers due to increased bulk. Adds an additional IS pip above the regular amount for that unit's weight in each location, including the head/cockpit, allowing for the increase of armor by 2 pts per location including the head/cockpit. It also lowers the overall cost formula. It can be used with Omnis with all the regular abilities/restrictions applied.). The Mongoose begin developing what they call the General-Frame or G-Frame which is an expandable mech chassis that can be easily adapted to any weight class cutting development time significantly.
When the Coyotes introduce the Omnimech, they are among the early Clans to capture Omnitech the year after the Jade Falcons do. They'll quickly combine it with their prototype G-Frame system giving them an exclusive series of Omnis to feild.
However they're one of the last Clans to gain Battle Armor or Elemental breeding protocols and when they do, their exclusivity to Clan Dart IIs, Targeting Computers and Modular IS have likewise ended. Clan ES IS remains far more popular but M IS is also adopted by the Blood Spirits, Burrocks and Coyotes. Other Clans mostly see it as a novelty. The Burrocks would develop their own Reinforced IS technology nearly two centuries later from this base while the Inner Sphere's attempt to duplicate it will be heavier and bulkier.
The exact canon Enclaves of Clan Mongoose are a little disjointed and unclear. In part due to their absorption and part TPTB glossing over those details. For the purpose of the AU, they maintained their capitol on Circe and an enclave on Strana Mechty plus held territories at times on Atreus, Kirin, Marshall, Tathis and Tokasha. Shadow is suggested as their possible capitol at Sarna but I haven't seen corroborating evidence yet to suggest they even had an enclave there. The AU avoids having the Marshall massacre but keeps the general raiding pattern the same otherwise.
By the 2880s, the Mongoose are one of the stronger Clans but still second tier compared to the Wolves, Jade Falcons, Coyotes, Ghost Bears, Nova Cats and Sea Foxes. While well equipped, their constant skirmishes with the Hell's Horses, Star Adders and Smoke Jaguars and a resurgence of the Blood Spirits and Fire Mandrills put then on the defensive, forcing them to engage with the Burrocks to search for new territory to exploit.
This would to discovery of two systems, approximately 60 LY E-SE of Niles and 25 LY further still East for the second. The first would be named Turquoise, after the inhabitable world with oceans of the same color. Closer to a Terra-like garden world in gravity, environment and ecosystem than most Clan worlds, it's sole failing grace is it's absolutely infested with native insect-like life. Grouped as Chitinoids by the Mongoose scientists, they're insect-like in only broad appearances and behavior, being much more advanced physiologically including a secondary internal pseudo skeleton and more complicated organ layouts. Many are much larger than Terran counterparts (1-2 inches) but a few species are gigantic (up to two feet). Fortunately the Mongoose's totem animal was found (with a little genetic engineering) to be suited as a biological method of control.
The second world would be named Darkeye. A large moon orbiting the remaining gas giant of a Red Dwarf system, the world is barely capable of supporting life, given it's tainted atmosphere. However, the planets algae-like soup covers the surface, both land and shallow sea, creating vast and easily harvested stocks of hydrocarbons and other chemicals giving the Darkeye considerable value.