Rainsford realizes that General Zaroff is toying with him, and he enjoys the hunt and wants to prolong it.

When Rainsford realizes General Zaroff hunts humans instead of animals, he is horrified.  He is even more disturbed when he figures out that Zaroff intends to hunt him.

Thank you, I'm a hunter, not a murderer."

"Dear me," said the general, quite unruffled, "again that unpleasant word. But I think I can show you that your scruples are quite ill founded."

Zaroff is convinced that he is doing right, or at least that he can do as he pleases.  When he forces Rainsford to be his prey, Zaroff demonstrates that he is a cruel man indeed.

The worst realization comes to Rainsford after he sees General Zaroff smile and turn away while hunting him.  This is when it comes to him that the general is toying with him, and trying to prolong the hunt.

The general was playing with him! The general was saving him for another day's sport! The Cossack was the cat; he was the mouse. Then it was that Rainsford knew the full meaning of terror.

After this, Rainsford realizes he is in over his head, and he is determined not to give up.  He uses every trick in the book, including the Burmese tiger pit and the Malay mancatcher.  Each time, he is unsuccessful and the general is pleased at his cunning.

Rainsford wins by throwing out the rules and using all of his cunning.  He manages to not only escape, but also find his way directly into the general’s room—where he wins the game on its own terms.

The slow characterization of General Zaroff allows the reader to come to terms with the gravity of what is going on in the story.  Long before The Hunger Games, this story was shocking people with its portrayal of flippant immorality.