Richard
What is Richard? In act 3 scene 2, Richard has a breaking point. He comes to a point where his humanity clashes with his destiny/title. His speech from line 144 through 177 shows his humanity with such lines as 167 "as if this flesh which walls about our life were brass impregnable." In context, he is saying that he is just as human as those around him just as in line 175 where he has a Shylock-esque quote, "I live with bread like you, feel want, taste grief, need friends." Richard has reached a point where hi title can no longer define him since Bolingbroke looks to be in position to take it from him, so he is starting to understand that he too is a man. This speech I think is the lynch pin of Richard's growth because what he says throughout the rest of the act is so blurry and muddled up by him saying words that others seem to be putting in his mouth. In the start of the play, Richard seems to be asserting his Kingship/manhood by starting to remove his uncles who never really gave him a chance to fully reign. At this point, Richard is realizing that he has no power unless it is given to him by uncles, citizens, or Bolingbroke. Richard is at a point of coming into manhood, however since he has to leave his boyhood behind,the Kingdom of England is left behind, and his short term as a man will be losing control and his life.


Becoming a Man
At first, I didn't really look at this as being the a time when Richard has to grapple with his role as a man, I originally just saw it as him having to pay for his mistakes, which I still believe it is. However, I agree with you. He is realizing that him being king wasn't absolute power, just a title that can be stolen or usurped. This is his defining moment and it makes it easier to understand why Richard truly has taken on a loose role of victim, for he is the victim of his own immaturity and misconception of power and manhood.
Veronica Sparks