The Asari use their functional command of the Eezo market and their built in advantage on Prothean data/tech (via thessia's ridiculous Eezo reserves and their Beacon) to essentially maintain their dominance of the citadel species. The Turians have an overwhelming military advantage over every other species which the Council sees fit to enshrine in law, laws which are backed by the Turians who have that massive advantage. The Salarians are canonically investing time and resources in covert uplifts and bioweapon research to improve their position relative to all the other races (specifically weaponized Varren and Uplifted Yagh).
The Turians consider the proper first contact response to seeing unknown ships from an unknown group with unknown markings in an unclaimed region to be blowing them up, calling in backup, and invading the planet of this new species. The Salarians consider good war policy to be developing a plague that ends in mountains of stillborn children.
There are at least ten sophont species linked to the citadel, more if you count former links which are now defunct. Of those species only three are granted any right to actually have a say in government. Species with no political representation include the species which created and maintained for two thousand years the entire financial system which allows for the other species to trade and interact on an economic level, and a species who saved the entire Citadel political system from being crushed by a bug war menace.
In the initial contact the Asari stepped in as peacemakers after their legbreakers had warmed up the Humans to accept being folded into client species status (client to the citadel council, not the turians of course). In the third game the Council grudgingly offers you dribs and drabs of support until reality finally drags them kicking and screaming to face the truth that everyone does in fact have to work together for mutual self interest, at which point it is very nearly too late.
All that is canon.
In the fic, humans make first contact, the aliens seem pretty friendly. Then some turians show up (much like canon) take issue with the ships hanging around the relay (much like canon) and start shooting (again, just like canon) and the aliens take the hit for the human's big ship (which, you know, is right then host to the Quarian ship's captain who is in talks to maybe get the quarians their first genuine ally in three hundred years).
And you're skeptical that the human establishment might possibly take that as an indication that A: the turians are jackasses and B: that the Quarians are pretty serious about being friendly since they just took a rail cannon round to protect a human hospital ship? Or that the Quarians might take an actual friend in the fucking universe as a damn good thing?
