"Conceal me what I am, and be my aid.For such disguise as haply shall become The form of my intent. I'll serve this duke: Thou shall present me as an eunuch to him" Viola survives in lllyria due to her mental streagh she didn't need to use any physical streaght to become part of Orsino's Court
Ralph and the rest of the boys needed to survive both the island and each other. Physical strength can only get you so far in a savage survival situation however the one that can survive comfortably is the one that keeps his composure and appeals to the mass. In this case Jack played on everyone's emotions and fears thus he got to become the leader, he didn't have to kill anyone to do it he simply used Ralph's weaknesses against him
Game of Thrones
Vary s in game of thrones came from poverty and through extensive study and mental strength he achieved one of the highest positions in the kingdom. He uses his mental strength to manipulate the world around him(the little birds) in order to survive, he has not used physical strength much throughout the show.