Jack's tribe offers an example of initiation by hazing the new tribe members. When Eric and Sam are brought into the tribe against their will at Castle Rock, Ralph discovers that Jack and Roger's savagery has continued:
"they made us. They hurt us--" (188).
The twins' conviction of Ralph being in danger is grounded in their own first hand knowledge of Jack and Roger's brutality.
"'You don't know Roger. He's a terror.
'And the chief--they're both--'
Earlier in novel, the reader sees evidence of Wilfred being beaten in the hunters' tribe, and the reader can easily draw the conclusion that Samneric suffered a similar fate as part of their reluctant initiation into Jack's tribe. Jack's abusive show of power is his way of proving his dominance over his fledgling tribe members.