Karsa may have started out *all* ego, fierceness of will, and headlong into chaos (almost literally due to the CG influence) but he has learned from his mistakes. I think he does think about consequences, but at the same time has so much confidence in his abilities (with just reason) that he will take, for him, the easy way out (brute strength) when it is the most obvious.
Icarium, I pity, as he is 'the ultimate weapon' yet needs someone to take care of him lest he be pointed in the wrong direction. If any of you have seen the film Memento, Icarium reminds me of the main character, only a nicer person. He relies on his philosophical meanderings in order to survive, says he wants to know the truth of his past, but can't deal with it when it is presented bluntly to him, because his sense of justice and logic can't accept what his rage does. I really like the analogy of Icarium as a Hulk-like character, spending most of the time as Bruce Banner with no knowledge of what he does when the emotion takes over. It would be a blessing in the long run for Icarium to be able to go into the Azath house with Gothos and truly be at peace with his actions.
Rhysel