In Romeo and Juliet, Shakespeare presents a picture of the Capulets and the Montagues. As the Prince says, the fair streets of their community, Verona, have been sullied by dueling and all kinds of conflict. But the conflict is so old that the families don't even remember why they are fighting. As the action of the play rolls forward, the two young lovers find themselves struggling to find a way to be together despite the problems between their two families. At the end, only their death serves to bring together the two families and bring peace to the streets.
In Lord of the Flies, Golding sets out to demonstrate the way that human nature will always trend towards violence and savagery without the rules and morals of civilization to hold it back. The boys who are stranded on the island are troubled by their fear of a "beastie" and the possibility that they are truly stranded. The fear eats away at their "community" and quickly they become savage and focused on hunting and violence instead of attempts to build shelters or get rescued as Ralph wanted originally.