Why does Renfield's behavior change so drastically dependent on Dracula's strength? Why does Renfield have his rages during times when Dracula is powerless, and why does he regain his lucidity when Dracula is powerful?
I think that Renfield's extremes are dependent on Dracula's condition because he has placed his stock in Dracula. Being Dracula's servant, whatever Renfield yearns will only be accomplished if his "master" is in a position of power. When Dracula is weakened, there is little hope for Renfield to accomplish his own hopes for power or immortality. Conversely, when Dracula is strengthened, Renfield is closer the achievement of his own subjective, something that lies outside the asylum in which he is imprisoned. Renfield's emotional state and his condition of perception are directly linked to Dracula's emergence and strength. It is this condition of being that makes his supposed betrayal of Dracula all the more poignant. Renfield puts aside his own lot to protect Mina from Dracula taking her blood, and thus, her life. This is the one instance where Renfield's rages and his emotional state are not tied into Dracula, recognizing that his obedience to his master should not come at the cost of Mina. In this instant, Dracula finishes off Renfield. Yet, prior to this, Renfield's railings and his intensity are contingent on Dracula's success and in this as Dracula goes, so goes Renfield.