It's sad if you've read the journals from the original game, and the novel "The Book of Atrus" which depict Sirrus and Achenar as very innocent seeming children. Compare those to what they turned into and ultimately ended up happening to them.
Atrus' situation in the very first game. Having to essentially kill both your sons because they grew up to be so evil? It's a wonder he recovers as well as he does.