Roger's never come up! While he dosen't have many quotes, you can say a lot about a little. For example, he's the only boy described as being "dark". While dark could be literal as in his hair being dark, being called 'the dark boy' links to the idea of darkness being in all men's hearts and Roger being the incarnation of evil in the novel. I shan't go into detail right now, unless it'd help anyone for me to do an essay style response?
It's been a while since Simon's come up, the island and conch are yet to make a return too.