At first, Roger is shy and withdrawn. Roger later becomes malicious. He has seemingly no conscience and is savage and simple-minded. He is around 10 to 12 years old and in grade six or seven.
Roger is kind of a sadist who takes pleasure in seeing other living things in pain or agony. Personally I think he is a rare kind of human-being, and that he is so aggressive and temperamental because of something that happened to him in early childhood.
I think that Roger is going to get really bloodthirsty and will want to hunt and kill other people on the island, and it will probably end up being a littlun since they are so defenseless, as well as they do not accomplish much on the island. He will almost definitely not compete among the other hunters though, for they pose a chance of hurting or killing him, and inside he is probably fearful of death.
Roger is a hunter, and he seems to carry a lot of side conversations at meetings. For instance, when Jack will say something, Roger will sometimes throw in a comment or two, usually having to do with violence or punishment.
For a while in the novel, he keeps to himself with an inner intensity of avoidance and secrecy, but when introduced to Jacks new tribe of hunters, Roger begins to open up and everyone sees his real personality. From here on, he interacts slightly more than he did before, only when the conversation regards to violence or something else that he seems to enjoy.
"He hesitated. The dark boy, Roger, stirred at last and spoke up. Lets have a vote" pg. 18. This shows that Roger was overly confident in the leadership of Jack, as the tribe voted for Ralph instead of him. It also describes him physically and mentally.
"Roger smiled, unwillingly. You don't half look a mess" pg. 66. This quote shows that he was caring in the beginning of the book, but the beast in Roger broke out. He takes pleasure in the torturing of living creatures as well as the littluns.
Sadists, killers, murderers, criminals, and insane people all represent Roger in real life.