The Ascent
The Ascent is an ancient hierarchy of species with the Kharmaani at the top, the Serpentids and Control Minds below them, and dozens of partially-uplifted member species below them. In recent centuries, the Ascent has begun to stagnate, but in the past they were a powerful, imperialistic civilization primarily motivated by conquest; they intended to uplift every species they could find and install them into a strict hierarchy, supposedly for their own safety and advancement. The Ascent's advance was stopped by the Skrell in an event neither civilization is willing to talk much about, suffice it to say that the Kharmaani were deeply traumatized and agreed to some fairly unbalanced peace terms.
In the current day, the Ascent and their subject species make up just under 60% of all membership on the council, although to their discontent they still only have an equivalent vote to the Skrell.
The Ascent enjoy fair relations with the Unathi and rapidly warming relations with Humanity; it was, in fact, the Ascent who overrode the Council's decision to avoid making contact with the humans and forced the Council to recognize them. Relations with the Skrell are especially bad, with the Skrell reluctant to negotiate on equal terms, and the Ascent unwilling to either engage with the Skrell as a subordinate or leave the council and risk another war.
The war between the Ascent and Skrell ended with a peace deal that left all of the Ascent's gains reversed, and bound them not to continue their course of invading and uplifting every species they found, and also set protocols for peaceful contact between the Skrell and the Ascent. This treaty remains in place to the current day, and adherence to this treaty forms the legal basis for the Ascent's continued membership in the council.