Jamison is probably clinically psychotic, or at the very least extremely delusional, to believe that a state which has very clearly and repeatedly confirmed its determination to totally subjugate humanity would grant any sort of clemency (she of course as noted earlier did it for her son, but I would think that given the history of the Kilrathi not only with humanity but with *every single species* that anyone with the capacity for reason could see a trend here....)
That's not true at all - you're actually arguing against the established facts. We know the Kilrathi didn't simply wipe out all the previous races they met. And, given how the war was going, it is quite conceivable that they would keep a prisoner alive in order to put pressure on Jamison.
Besides that, you're arguing from some kind of bizarre perspective where people are either 100% rational, or clinically insane. Reality is nothing of the kind -
nobody is ever rational, and hardly anyone is clinically insane. Jamison certainly wasn't. It's hard to think of better proof of a woman's
sanity that she would do anything she can to protect her son. Yes, she should have known that there was no hope he'd live - but it's not something that's easy to accept. Ultimately, Jamison is not even an especially evil character - she's merely tragic.
(heck, going by your logic, Spirit was clinically insane too)
Of course, Jamison is hardly alone in this; the whole Society of Mandarins are a group of clinical lunatics (something even a second-liner like Shadow can see.) They look at the history of great human civilizations (Rome, for instance, or the succesive Chinese empires from which their name derives) and see that, historically, the conquerors have frequently become domesticized by the cultures they conquer, effectively becoming the conquered. They ignore the fact that these civilizations met their fate at the hands of rough-hewn barbarians for whom the glittering cities must have been amazing wonders. The Kilrathi are not barbarians; they possess an extremely sophisticated culture of their own and a level of technology on par with humans, and of course they are far more powerful physically and much more violent. Human history has known parallels to this, but never to these extremes; I don't think it's seen much in science fiction, either.
Again, you're ignoring the established facts. The Kilrathi are not blood-thirsty mass murderers bent on wiping out humanity. Their objective, when the war was first started, was to conquer and
enslave mankind. They already had millions, more likely billions of slaves. They attacked mankind with Varni-manufactured torpedoes.
What would happen had the Kilrathi been able to achieve easy victory? Logically, the easier their victory, the more slaves they would have had, and therefore, the more they would themselves have become reliant on slaves. You have ten slaves, you'll manage them yourself with a whip. You have twenty slaves, you'll hire someone to watch over them. You have a thousand slaves, and not only will you hire people to watch over them, but you'll also pay some of the slaves to form a sort of internal government. Even in the Warsaw Ghetto, it wasn't the Nazis alone that drove Jews into the trains headed for Auschwitz - they had a specially-established Jewish police force assisting them. Similarly, after occupying Germany, the first thing the Soviets started looking for was German communists whom they could appoint to govern the country in their stead. With hundreds or thousands of entire
planets inhabited by human slaves, who knows if the Kilrathi wouldn't have actually signed some kind of "treaty" with the Confederation, whereby a Mandarin-ruled Confederation would become a vassal state.
So, there was nothing insane at all about the Mandarins' plan. Had the Kilrathi won, the Mandarins would most likely have indeed been chosen to govern mankind. Of course, even then, it's hard to imagine the Mandarins converting the Kilrathi to human culture... but who says that was ever their goal? Communists also always argued they were fighting to establish equality and freedom and all, but in reality, whatever the rank-and-file members may have believed, the higher-ups in their parties always fought only to establish their own power and fortune.
About the only thing that the Mandarins overlooked was the changing nature of the war. The longer the war went on, the more the Kilrathi leaned towards the option of wiping out mankind entirely. But then again, they also respected mankind more and more. It wasn't until the truce that the Kilrathi not only lost all respect for humanity, but also decided to wipe them out (...a decision that either was ignored, or quickly taken back - in spite of Thrakhath's order to kill all the human slaves, Confed still liberated a few slave camps in the last year of the war).