Oliver de Boys, Jaques de Boys and Orlando de Boys are the sons of Sir Rowland de Boys. Before Sir Rowland de Boys died he gave all his property to his elder son Oliver as per the traditions. In his fathers will Oliver was to look after his younger brothers. The will also asked Oliver to give them thousand crowns. But Oliver was envious of his brother Orlando because everyone including his servants liked Orlando better and so Oliver ill-treated his brother Orlando. But he send his other brother Jaques to school and treated him well.
This caused tension between the brothers and one day they had a fight and at the end Oliver was forced to give Orlando his thousand crowns. In the process Oliver tried to kill Orlando two times. Once by asking the wrestlers Charles to not only defeat but also kill Orlando in the wrestling match. When that mission failed he himself tries to kill Orlando by setting fire to his room while he is asleep. This mission too fails due to the timely warning of the servant Adam.
The two brothers did not meet each other for quite some time but after the flight of Rosalind and Celia the Duke asks Oliver to go in search of Orlando for the safety of his own life since he believes that the girls have ran away with Orlando.
Oliver in his search for Orlando ends up in the forest of Arden and there Orlando saved him from being killed by a huge poisonous snake and a lioness. This causes the softening of his attitude towards his brother.
This way at the beginning of the play Oliver was cross with his brother but by the end he started liking his brother.