From the Novel:  The LORD OF THE FLIES MIKE GOES CRAZY

Jack is played by Mike.  He goes crazy and breaks away from the tribe.  Only to end up killing piggy for the fun of it.

Piggy is played by Gay boy Jeff.  See they both have glasses, I see some similarities.  We can hope that the blood we saw on Mikes face was that of Jeff's in the next episode.

THE THIRST FOR BLOOD CONTINUES