When allegations that DPRK leader Kim Jong-un had his half brother, Kim Jong-nam, murdered in a Malaysian airport, first surfaced, the general response was to assume that the Kims are just crazy.
After all, what possible reason could he have to whack his own flesh and blood?
Well, if said half-brother is a CIA asset, which technically means that he is working with people trying to overthrow you, it’s a reason.
In fact killing an exiled relative who is trying to overthrow you has a lot of historical precedent.
It doesn’t meant that Kim Jong-un isn’t a nasty piece of work, but it does mean that he is sane, which is reassuring, because a rational adversary is more predictable.