In the beginning of the play, Orlando and Oliver's relationship can only be characterized as hostile. Orlando explains in his opening speech that when their father passed away, their father left a thousand crowns to Orlando in his will plus commanded Oliver to see to Orlando's education as a gentleman. In his opening speech, Orlando is explaining to the faithful servant Adam how distressed he is by the fact that he has not received his proper education. In contrast, Orlando states that Oliver has seen to Jaques' education, their youngest brother, but not his own. Orlando proclaims he feels he is being treated by Oliver even more poorly than the estate animals, as we see in his lines:
His horses are bred better; for, besides that they are fair with their feeding, they are taught their manage, and to that end riders dearly hired: but I, his brother, gain nothing under him but growth. (I.i.10-14)
Literary critics have speculated that Oliver feels jealous of Orlando for his "talent, generosity, and aristocratic impulses" but does not feel the same sort of jealousy towards Jaques, resulting in Oliver allowing Jaques to be educated but not Orlando (eNotes, "Oliver (Character Analysis)"). As a result of this animosity between the two brothers, the play opens up with a fight in which Oliver tries to strike Orlando, but "Orlando gets the upper hand" (52-53). As a result of the fight and his jealousy, Oliver also plans to have Orlando killed by wrestling the duke's court wrestler, Charles, but Orlando actually wins against Charles. Next, Oliver plans to burn down Orlando's lodging, but Orlando and the servant Adam escape into the Forest of Arden.
However, by the time we reach Act 4, Scene 3, the two brothers' relationship changes significantly. Oliver was sent into the Forest of Arden by Duke Frederick in pursuit of Orlando. We learn in Act 4, Scene 3 that Orlando discovers his brother Oliver asleep under a tree in the forest and about to be attacked by a lioness. Orlando almost decides to leave Oliver to his fate but then decides to fight the lioness, saving his brother's life and becoming wounded in the process. Oliver was so moved by Orlando's act of bravery and sacrifice that he becomes a changed man who now loves his brother.