A good quote to examine when considering Roger's character is the scene in which Roger practices throwing stones at Henry but chooses to miss:
"Here invisible, yet strong, was the taboo of the old life. round the squatting child was the protection of parents and school and policemen and the law. Roger's arm was conditioned by a civilization that knew nothing of him and was in ruins" (62).
This quote from Chapter Four reveals Roger's reluctance to trespass the boundaries of civilization. This scene with Roger occurs fairly early on in the novel when the presence of law and order was still strong in the boys' minds. It is interesting to note that the things that hold Roger's arm back, teachers, parents, school, are all exterior sources of motivation to behave correctly and do right; there is no mention of Roger's morals or conscience convicting him. Later as the boys descend more and more into savagery, those old restraints will not be there, and Roger will have no qualms about using violence against the other boys.
I had studied this book a few months ago and I even had to write an essay on it. :)
Roger is a very mean and ruthless boy, who along with Jack taunts the younger kids and behaves malevolently with them.
The young boys who had no experience in the world had turned barbarous. They now had the liberty to do what they please. On page 114, the boys scream, “ Kill the pig! Cut its throat! Bash him in!” This is very unusual behavior for twelve year olds who are now talking about killing another living beings ruthlessly.
Roger is also a part of this gang, and hence I specifically think it is a very good example for character.
Also, Roger is the guy who throws the rock on Piggy, killing him, hence we can conclude he is a horriblly disgusting boy.
Please let me know if you need more help. :)