I feel like B has a lot of options and can open a romantic dialogue easier.
Yes macbeths character changes throughout the play. In the begining he is loyal and brave. He doesnt want to kill king duncan because they are friends and he gives him a new title. But his wife and the witches changes his mind, and he wants to become king, so he goes with his wifes plan to murder the king. I believe he starts to change in act 2, i am not 100% sure thoe!
Good luck!
