The Captain is an animal-trainer at a circus, and he treats the tiger with appalling cruelty. As with all wild animals at the circus, the tiger's expected to perform tricks for the crowd. But he's a proud animal, a wild animal whose natural habitat is in the forest; he belongs there, not in a circus. The Captain may have trained him to do tricks, but no matter how hard he tries, he’ll never be able to change the tiger into a domesticated animal.
And so it proves when, one day, the tiger turns on the Captain and brutally mauls him to death. Such behavior isn’t out of character for the tiger; he attacked and ate some of the villagers’ livestock as revenge for his family’s being killed by poachers. But as his friendship with a local monk later on in the story testifies, the tiger only does harm to those humans who do harm to him.