In chapter three, the other boys view Simon as a bit of a misfit. He is one of the only older boys who is actually helpful to Ralph and builds huts on the beach for the littluns. The littluns see Simon, who helps them get fruit off the high-hanging tree branches, as someone who is approachable, not like the intimidating, fierce Jack.
Simon represents common decency and kindness; because of this, he does not really fit in with Jack's hunters who perceive his goodwill toward the younger boys as weakness. Ralph, on the other hand, appreciates Simon's help and assistance, knowing that Simon is someone who will be fair and can be depended upon.