In Chapter 2 of Lord of the Flies, the littluns, the little boys who for the most part aren't given individual names by Golding, have been playing contentedly on the island. Some pitched in with gathering some sticks for firewood, but mostly they have been running free, playing on the beach and in the woods. The only child who has expressed fear is a little boy with a mulberry colored birthmark on his cheek who relates his fear of the "snake-thing" or "beastie" he has seen. When the older boys discount his fears, the littluns return to their play.
However, in Chapter 3, after the fire the boys built has destroyed part of the island and the boy with the birthmark can't be found, all the littluns become fearful. Ralph points out the change in them to Jack. He explains that the littluns dream at night and that he can hear them, meaning they are having nightmares. They talk and scream and behave "as if it wasn't a good island." This shows that the littluns have developed beyond thinking being alone on the island is a game and have become frightened. Although they focus their fears on "the beastie," it is actually just a way of objectifying the terror that they feel as the novelty of their situation wears off and the reality of it begins to sink in to their young minds.