Well, my little brother has the propensity to be caustic, to put himself in nightmarish situations time and time again, and has framed me and other siblings for grievous acts of betrayal and of putting myself in messed-up situations of the sort he would most assuredly put himself in in a whim. He has consistently proven his adepthood in the arena of lying and manipulation. He constantly creates drama, and with time has become more destructive.
As an example, he once framed one of my more distant relatives, telling my other siblings that the aforementioned relative backbited them. One of my siblings proceeded to backbite in turn, and my little brother proceeded to expose my sibling to that other relative.. What destructive buffoonery is this? He has also laughed at the misfortune of our siblings, me included. Maybe he sees our misfortune as us putting ourselves in sick scenarios, which he would understandably enjoy, in voyeuristic glee. Not so jarring at this point, as his tactics have gotten old.
After a few weeks of personal investigation, of intensively exploring the inner landscape of my little brother (cross-referencing accounts, etc.), I have only become convinced of his sinister nature. I have given him the benefit of the doubt countless times, but alas, it was for nothing. Even his parents are aware that something is "off" with him.
I confronted him, and told him that from now on, I will only interact with him in formal terms, and that I expect the same from him, that a "safe space" will exist between him and I; any violation of that will result in me taking revenge (in other words, playing along his system of morality, which must be externally enforced). I also said that I will come back and avenge our nuclear family at the extent he realizes his destructive potential towards us.
How else do I deal with such a person? Do I sit back and enjoy the show? After all, there was a time when psychopaths were pushed off a cliff while no one's looking. But that option is no longer with us.