Which character is the most powerful in this novel? Which character is the most powerless? How do characters react to being powerful or powerless?

These are pretty daunting questions. I think there are two levels to power at play in the book. There is the exterior world of power where the men in the hospital submit to Ratched's control. Then there is the interior emotional world where power isn't so defined. Ratched represses her own sexuality and feminine identity to wield the kind of power she does. Really though, she is powerless when her repressed interior is shown to the men on the ward. McMurphy looses both gains and looses his power when he physically tries to kill Nurse Ratched. These complexities of give and take eventually lead to the concept of power destroying both Mcmurphy and Ratched. This distruction , however, gives Chief Bromden the power to liberate himself.