Ralph versus Brutus-- What do they have in common?
The best way to compare Ralph to Brutus from Julius Caesar would be to do so through the lens of order and "doing what is right." Both characters come across as being incredibly moral people. Ralph believes in maintaining order and doing his best to take care of the littluns and other boys, all the while maintaining a signal fire to aid in their rescue. Like Ralph, Brutus also believes in order; he intensely values the Roman Republic, so much so that he is willing to aid in murdering a friend to achieve it.
Murdered a friend
Not a pretty detail to reflect on, but both Ralph and Brutus murdered a friend. Brutus aided in the murder of Julius Caesar, whom he claimed to "love [...] well" (I.ii). Similarly, Ralph participates in the group slaying of Simon, caught up in the bloodlust of Jack's dance. Interestingly enough, another major parallel is that both of the murders occurred in groups. Later, both Ralph and Brutus openly admit their regret at their actions as well.