What motivates Ivan and General Zaroff?

Ivan is General Zaroff's Cossack bodyguard and servant, who attends to the general, protects him, punishes unruly prisoners, and helps him hunt humans. Ivan is portrayed as an unintelligent person, who takes pleasure in torturing the prisoners that refuse to participate in the general's game.
Similar to Ivan, who has an affinity for torturing prisoners and is a rather violent man, General Zaroff also takes pleasure in hurting people. General Zaroff is a fanatical hunter, who attempts to satisfy his desires by hunting humans on Ship-Trap Island. The general admits to Rainsford that he is driven to hunt humans because he enjoys the challenge of hunting rational, intelligent beings.
While the general insists that he is a civil person, he is depicted as a ruthless, bloodthirsty murderer. Overall, what motivates both Ivan and General Zaroff is their affinity for harming individuals and imposing their will on defenseless people.