twins

"Coriolanus's and Aufidius's relationship is a self-defining dialectic of dominance/submission, an obsessive power struggle with homosexual overtones...on the contrary Coriolanus's emotional identification with Aufidius makes possible self-definition-Coriolanus's inability to distinguish between the actual, potential homicidal Aufidius and his own fantasy of an ideal twin that proves fatal for the hero." pg. 2
Coriolanus and Aufidius develop an unique relationship throughout the play. In one sense Coriolanus is the yin to Aufidius's yang; they complement each other. This is shown by Coriolanus's (honor) superior military policy and Aufidius's (policy) superior political policy. Another aspect is their desire to be one; they are twins of the same people who steal the others identity. Therefore, Aufidius's comments on Coriolanus's weaknesses also apply to himself which bring him to his own downfall (by plotting and killing Coriolanus). In their desires to be each other/ have the others identity, they are both enemies who desire each other (in a union, or perhaps in other ways). After their union though, their relationship is ruptured when Coriolanus rises above Aufidius. Their relationship is no longer equal and Coriolanus is the superior self, which leads to Aufidius destruction of the superior self (of himself).
Also, I would like to point out that both men have extremely large egos of themselves. They love themselves so much that when they see their self represented in another body, they are inclined to have affection and desirous feelings toward the other person.