Killing Your Friends and Father for Fun & Profit

I've been reading Usama ibn Munqidh's Book of Contemplation lately. Ibn Munqidh was an aristocrat who lived in 12th-century Syria, and his Book of Contemplation is about fate, and is mostly illustrated with events from his own life. It's also of interest because we get to see a bit of the Crusades from the Muslim side.

One event in the book has gotten me thinking about the problems of understanding other cultures -- not just other ethnic cultures, other religious cultures, or cultures separated from us by the long centuries of time, but also differences in social class.

We're told by UiM that "Al-Zafir [a caliph] now concocted a plan with Nasr [an amir of the same age, and son of the vizier 'Abbas], convincing him that, in Nasr killed his father, he would appoint him to the vizierate in his place." Later UiM hears about the plot, and warns Nasr that to kill his own father would leave him damned come the Day of Judgment. "He [Nasr] later acquainted his father ['Abbas] with the whole affair. So the latter behaved kindly towards him, won him over -- and plotted with him to murder al-Zafir. Al-Zafir and Nasr were the same age, and they used to go out together at night in disguise. So Nasr invited the caliph over to his house [....] As soon as the caliph was all settled in the sitting room, Nasr's men rushed out at him and killed him." (Paul M. Cobb's translation, Penguin edition).

Here's my problem with this -- I have trouble conceiving of this social situation arising at all. When I look at the family life of, say, Henry II, it doesn't make a lot of sense to me, but this is even more difficult to understand.

I try to imagine fictionalizing the dialogue, and can't come up with anything that would sound even remotely believable to modern audiences. Let's say two friends are out on the town -- how do you get around to "Hey, let's kill your dad!" And then, even assuming you're down with that, later telling your father about it, who says, "Hey, let's kill your friend!" It can't be true that all Syrian aristocrats were sociopaths, but the matter-of-fact way ibn Munqidh writes about it, and the number of people involved in the subsequent bloodbath makes it seem that way. Somehow this situation was a natural outgrowth of world they lived in.