Iteration, improvement, contest.
This has always been the driving purpose of the rachni. Before the rachni became the rachni, this was the struggle of all against all; then, in prehistory, the war of Queendoms against Queendoms for resources and territory. Struggle, contest, competition - these are all a vital part of the Cycle of Improvement, vital spurs to learning and innovation.
But the Cycle itself is subject to the same forces of improvement. War and Conquest are a basic and primitive form of contest - inefficient, destructive, wasteful. Just as new forms of Rachni are developed by the Cycle, so too can new forms of contest be pioneered, and even entirely new rotations of the Cycle itself.
Enslavement is not one of them. While it promises great advantages, enabling great power and resources for those who enslave the defeated, it is in truth a vicious trap for both slave and enslaver. The short term advantages that it provides to the enslaver only lead to long term stagnation. Instead of seeking further improvement of self, the enslavers must become devoted to keeping the enslaved weak enough to remain beneath their yoke, precluding the opportunity for further contest and growth. Witness the fate of the Protheans. And worse yet is the Reapers, who would make all the galaxy resonate to their sour monotonous drone.
Cooperation is. It enables those who have sought improvement through utterly divergent paths of iteration to learn and seek inspiration from each other, and yet it does not preclude - and can even encourage! - new and less destructive forms of contest and competition in which all gain and nothing is wasted. See how our cooperation with the geth led us to compete and match their undertaking, and inspired the creation of the new and incredible rachni Princess form; behold how the peoples of the Citadel have grown mightier together.
Let us seek to make something grander yet - a Grand Galactic Harmony in which all can freely and willingly work together to learn, compete, and seek inspiration, all in pursuit of ever greater improvement together.
[X] (Grand Ambition) To create a Grand Galactic Harmony.
[X] (Feelings towards non-rachni) Fellow competitors and sources of inspiration, potential singers of the Grander Galactic Harmony.
[X] (Beliefs and Philosophy) Iteration, Improvement, Contest.
Our old martial philosophy was one that worked well for our Reaper masters, who saw the children of the rachni as disposable tools. In the end, that doctrine was insufficient. It failed, and is a wasteful path besides. Now we are fewer in number than ever, we cannot and should never send our children to die in their multitudes so that a few queens might survive. Let us instead learn from our geth allies and from those who have dominated this galaxy for so long, the asari and the salarians. Is that not a more fitting strategy for us in any case, matching more the path we pursue rather than what we are viewed as by outsiders? We are not some mindless devouring swarm - our children are specialists, designed to excel in their roles. Let us take this strategy farther!
[X] Elite: Every piece of equipment is top-of-the-line, every ship is a masterwork of precision engineering, every soldier is a well-trained specialist. You hit like a dreadnought and take a hit like one too, but hopefully, you won't have to do so in too many places at once.
Past/Present users: Asari Republics, Salarian Union, Geth Consensus
+Tech (Fleets and Armies count as one Tech level above your Civ. Tech Level)
-Numbers (Fleets and Armies count as one Magnitude below their listed magnitude)
If the asari and the salarians are those who have dominated the galaxy for a long time for a reason, then we can also learn from those rising upstarts, the people of the Shepherd, who swiftly move to take a powerful position despite their brief position on the galactic scene. Let this be a testing ground of our great ambition - let us seek to orchestrate a new harmony by learning from both the Old and the New, and adding the teachings of the Old Citadel Races to what we can learn from the Newest.
[X] Carrier - Carriers are a very new concept to naval warfare that you are amazed the Rachni never thought of before. Introduced by the System's Alliance, capital-class fighter-carriers are more flexible and less overtly threatening than conventional dreadnoughts and mesh exceptionally well with the (historically) highly effective Rachni strike craft. This entirely theoretical doctrine shares the balanced doctrine's numerical disposition ratios but would focus the Fleets on supporting and protecting Fleet and Patrol carriers, which would almost entirely replace Dreadnoughts within the line-of-battle as heavy damage dealers, with other vessels devoted to screening them from attack by enemy cruisers and dreadnoughts.
If we would pursue of our ambitions, we cannot stay forever in hiding. In the longer term, a great bunker would only be a glorious treasure for the Reapers who would enslave us once more; in the short term, we should reject the entire philosophy that would conceal the eldest queens away on great sanctuary worlds while we send our young to die in their stead. The ships we send out to fight and protect us and harmony itself must be as mighty and beloved as our children are; nonetheless, we should not overlook the importance of supplying these, and the advantages we can bring to bear there in specialised builders, workers, and administrators. A well-supported sword is mightier still.
[1] Expansion of military infrastructure - A sword is only as good as the sheath to stop it in, or the stone to sharpen it. Your fleets and armies will need shipyards to conduct repairs, refits, and expansions, resupply points, housing for their troops and crew, and an industry dedicated to producing the materials needed to keep everything running smoothly. All of that takes resources, resources that cannot be easily retooled for other purposes.
[2] Expansion of the fleet - In the interstellar age, a species is only as dangerous as its Void-Navy. Hulls and Guns equal power, and with a whole galaxy hostile to you, having a sword with which to keep them at bay will be vital sooner or later. Best to make it one big sword while you have the time.
[3] Expansion of ground forces - In the days of the Old Empire, the Rachni were terrors in the field of surface warfare, unmatched by anything the Citadel could muster until the Krogan entered the war, and absolute hell to dig out once entrenched. Though newcomers like the Turians and Humans likely make the field slightly more even nowadays, that is an advantage you very much still hold. Best to be prepared to exploit it.
[4] Expansion of planetary defences - One of the Rachni's greatest strengths has always been their ability to fortify their worlds-having the majority of their infrastructure located in underground hives certainly makes taking them much harder than invading biped worlds. But often, more dedicated defences are called for. Bunkers, bases, anti-orbital mass accelerators, GUARDIAN turret arrays-all of these and more will be needed to protect Hallownest and the other colonies in the event of the worst.