Indirect characterization has to do with implied descriptions or comments about characters in a story. An implicit description is not explicit; that is to say, the description is not direct or clear. Therefore, the reader must use inference to come to conclusions about characters' personalities, philosophies, or physical traits. For example, when Rainsford falls off the yacht at the beginning of the story, he swims for the island and makes it safely there. He's exhausted, but he makes it! This proves that Rainsford is physically strong enough to fight the currents of the sea when forced to survive. Not only that, but Rainsford is strong mentally as explained in the following passage:

"A certain coolheadedness had come to him; it was not the first time he had been a tight place . . . He wrestled himself out of his clothes and shouted with all his power . . . and doggedly he swam . . . swimming with slow, deliberate strokes, conserving his strength. For a seemingly endless time he fought the sea."

The above passage does not come out and tell the reader directly that Rainsford is mentally and physically strong--he just knows exactly what to do in any survival situation. The narrator also doesn't explain how or why Rainsford knows what to do. For instance, how does Rainsford know to "wrestle" himself out of his clothes, and how does that help him? A reader would have to infer that his clothing could drag him down deeper into the water and make swimming more difficult. The text merely implies that Rainsford just knows what to do. One might also infer that Rainsford is not only a renowned hunter, but he is also familiar with the outdoors and survival skills. Furthermore, his "coolheadedness" suggests mental strength and reasoning skills which will also serve him later when Zaroff hunts him like an animal. 

Next, General Zaroff's character is revealed little by little as he explains his philosophy about hunting and eventually that he is willing to murder humans to satisfy his boredom. However, the reader gets an indirect look at how General Zaroff plays his game as Rainsford discovers it himself. For example, when Zaroff finds Rainsford the first night, he doesn't explicitly say that he knows where Rainsford is. The text indirectly reveals Zaroff's sinister character, and as a hunter, as follows:

"The hunter shook his head several times, as if he were puzzled . . . The general's eyes had left the ground and were traveling inch by inch up the tree . . . But the sharp eyes of the hunter stopped before they reached the limb where Rainsford lay; a smile spread over his brown face. Very deliberately he blew a smoke ring into the air; then he turned his back on the trees and walked carelessly away . . ."

Based on the above passage, the reader can infer that General Zaroff does not give up when he is puzzled, and he has the intelligence to figure out what Rainsford does to survive on the first night. We also learn that Zaroff's "sharp eyes" stop before actually identifying Rainsford in the tree. This suggests that he doesn't want to end the hunt right away. Then, after he walks away, the process of inferring continues. Why does he leave if he knows where his quarry is?

Rainsford uses inference to come to a conclusion about Zaroff based on the behavior that he sees. On the same note, the reader can infer from the indirect descriptions that Zaroff wants to prolong his hunting time with Rainsford because of his need for entertainment and sport. To Rainsford, this is a life or death situation; but for Zaroff, it's all just a game. The narrator, however, does not come out and say this directly. That would take away from the narrative nature of storytelling. The good thing about indirect characterization is that it allows the reader to construct a vision of the characters' personalities, philosophies, and physical features from nuggets of information provided in the text.