One of the things that made Shakespeare a great writer was his ability to create realistic characters that reflected people's needs, desires, and conflicts. He took as much care with minor characters as he did with his main protagonists. In the case of Oliver in As You Like It, he looks at what drives a person and how that person can change. Oliver was jealous of his brother Orlando because Orlando was the favorite. Oliver judged Orlando by his own character, expecting him to be grasping and jealous, too. He did not see that Orlando was not interested in the same things he was. He was insecure and afraid, so he tried to have Orlando killed. He felt threatened by Orlando's strength and confidence.
What changed him, however, was love. When he met Celia and fell in love, he was able to look at things from a different perspective and see truly that Orlando was no threat to him. The two brothers' characters mirror the characters of Duke Senior and his brother, who experienced much the same conflict as Orlando and Oliver. Since the play is a comedy, all is resolved at the end. Duke Senior is restored to his court and the play ends with multiple marriages and reunited brothers .