Why does Jack hate Ralph in "Lord of the Flies"?
Their antagonism becomes more and more open, even though Ralph went through some common danger hunting with Jack - and this would usually bring them closer.
Jack is a bully by nature. He leads by intimidation. Our first glimpse of him is as he marches a troop of boys, fellow choir members, down to the beach where Ralph and Piggy are right after the crash. He's the head of the choir and he had the boys, in their long, black choir robes and caps, marching in the hot sun. It's clear right away that the boys are intimidated by him. It's also clear that there are two boys who are the oldest and most capable of being in charge - Ralph and Jack. When Ralph wins that election to become the chief, Jack is immediately jealous. We are told that as the other boys applauded Ralph's victory, "...the freckles on Jack's face disappeared under a blush of mortification." He was a boy accustomed to being in control and he not only lost this vote, he lost it in front of those he had been controlling. After this the dislike that Jack has for Ralph begins to grow and by the time of the second election, in which Ralph again wins, Jack hates Ralph and is determined to take him down.
The reason why Jack hates Ralph and Piggy is because the two latter are capable to leading the group. Jack hates Ralph because he was chosen leader instead of Jack. This however angered Jack because he is used to always being in charged and leading.