TMF: Just an idea that I had after seeing the Turians being portrayed as utter monsters over and over. A quote came to mind from a favorite author. "There are always reasons but never excuses."
Disclaimer: I own jack, zilch, nada, nothing, etc etc etc. Don't sue me.
2157. A year more than any other emblazoned across humanity's collective psyche. First Contact. Humanity was not alone. However First Contact did not go as hoped.
Emerging from Relay 314, Humanity was met with an unyielding and uncaring military juggernaut. One known simply as the Turian Hierarchy, unrelenting the utter subjagation of their foes, and pitiless to pleas of ignorance. Horror stories circulate still of the tactics employed by Turian commanders in their pursuit of victory. Towns obliterated by artillery fire. Firestorms started and left to rage in areas of probable resistance. Children held hostage to prevent prisoner rioting. All these and more occured over the assault on the besieged world of Shanxi.
Years after the war, critics still rage at the inhumane practices of the Hierarchy. Terms such as proper rules of engagement, and unacceptable tactics are common to the point of being pedantic. Few of Humanity, however, seek out the reason such practices are an established part of Turian military doctrine. Fewer still try to understand why the Citadel galactic community accept such a harsh and intractable species as allies.
Salarians see Turians as a necessary component to a complete plan, one that pushes forward the Unions interests no matter the cost. Volus see Turians as a stable market with just enough flux to stay from being stagnant. Hanar see the Turians as another lost group to bring to the redeeming light of the Enkindlers. Above all though, Asari remember the fear of the encroaching Krogan threat, the shame forced upon too many daughters of Thessia, and the utter relief in finding a race that could push back the terrors in the night no matter the cost.
In the extreme case that a human actually delved into Turian history, to actually find the underlying reason for the implacable will to crush a foe so utterly that no chance of a retaliation existed, they would need to look no further than the Unification Wars. A forty year span of carnage and atrocities perpetrated by Turians against their own people. The Invictus massacre that left thousands dead at the hands of proud colony freedom fighters. The Parthia Impact where a thriving city was turned into a little more than a crater when Thracian pilots guided asteroids on a ballistic course. The blood soaked list stretches on and on, a testament to unwillingness to completely stop the fighting by the then unwilling Hierarchy.
The final straw was when a bioengineered plague was released on Aephus. Despite their being no obvious culprits it was utterlt clear the last line was crossed and Turian culture was changed irrevocably. Like a whirlwind the previously complacent Hierachy went on the warpath at the urging of its people. No more was there multiple offers of quarter given, or prisoners afforded dignity. Too many corpses had shown that the only response that would unilaterally work for better or for worse was an inexorable war machine that moved on only when there were no weapons to lift against the Herarchy or hands to wield them.
History showed that total war pacified the colonies completely in the Unification War. That same war machine ground down and finished the fearsome Krogan Rebellions. The Batarian Hegemony went from a dark star rising to a pitiful remnant of an empire kept alive at the whims of the Council. So when Humanity complains at the unnecessary cruelty of forces, the Turian Hierarchy simply remembers that they have not faced the terrors in the dark nor did they have to watch a civil war ravage theit entire race. Humanity is far to new to a cold cruel galaxy to understand the lengths needed to preserve order and peace.
For a Turian, any cost is better than having to go back to those dark times of fear and senseless death. No matter the consequences, Turians will uphold the peace, for no price too dear to consider.