Exhausted and resigned (and incredibly fucking turned on), he watches because (he wants to see it and) he is afraid to do anything else.

Defeat is a good look on him, isn't it. At some point in the last ten minutes, he stopped resisting, stopped keeping up the pretense that anything he does might matter. No more arguing, no more smart remarks, no more futile efforts to move away from Obadiah's hands. Just silent cooperation—silent except for the way he whimpers, with fear and discomfort when it feels like it's too much or shameful pleasure when he starts to like it.