In "Lord of the Flies", is Jack or Roger the stronger beast within?
Jack has the stronger beast within him and he has less ability to keep that beast inside. When Jack fails to kill the pig at the end of the first chapter, he vows that he won't fail again. The reason he couldn't kill the pig was that he wasn't savage enough yet; the civilization within him kept him from being able to shed the pig's blood. This failure humiliates him because he sees it as a weakness which means that he sees failure to be savage as a weakness. When Simon is killed at the end of chapter 9, Ralph is upset to the point of distraction. Piggy, at the start of chapter 10, has to convince him that what happened was a horrible accident. Jack is much more willing and eager to let the beast out while Ralph continually works to remain civilized. He dislikes even being dirty and unkempt while Jack makes himself even dirtier when he rubs soot and clay on his face to make a mask. Ralph continues to try to use reason even in the last chapter as he tries to convince Sam and Eric to help him. When the boys are finally rescued, Ralph cries for their losses.
Jack and Roger both have a definite tendency towards evil. Jack shows it more, while Roger just kind of hides in the shadows. Keep in mind that throughout the book, Roger seems to find a lot of pleasure in causing pain for others. He is definitely a sadist. He is the one who sticks his spear into the sow's butt, and he intentionally kills Piggy. Although Jack is definitely cruel, don't underestimate Roger.