The origin of Armus is mythical in a Jack Kirby sort of way. The “tar” is the physical manifestation of all the negative emotions and psychic impulses of a long-forgotten species of unnamed “Titans” who used advanced technology to literally rid themselves of hate. The Titans then left their world and abandoned their sticky, tar-like hatred. Over the years — centuries? millennia? — Armus evolved from that hate into an intelligent being. Armus is, like Changelings, a living liquid and has no internal organs or skeleton. It can move around and alter its density at will, and also clearly possesses advanced, terrifying psychic powers. Its powers also involved a far-reaching psychic field, which was why the Enterprise couldn’t beam Troi to safety.
Armus isn’t harmed by phasers, and, at one point, sucks Commander Riker (Jonathan Frakes) into its body. While inside, Riker is seemingly reduced to a liquid state wherein he is savagely tortured. Armus then reconstitutes Riker and spits him back onto the desert floor of Vagra II. At a convention attended by this author, Frakes admitted that he actually had to climb into a pool of ink-black Metamucil, an unpleasant experience to say the least. This story, however, was contradicted by the “FX Journal” which stated that Frakes’ stuntman was used for the submersion scene.
As a being of pure anger, Armus didn’t behave entirely logically. It had been alone on Vagra II for God knows how long, waiting for torture victims to stumble into its path. When victims did appear, however, Armus did everything in its power to frighten them and scare them off. It longed for company, but only required that company in order to alienate them. In short, Armus was your average Twitter user.