Sibling love/rivalry

As anyone with siblings knows, fighting is inevitable. However, underneath it all we still love each other. When reading Act 4 Scene 3, I saw Cassius and Brutus to be very much like brothers. They were bickering a lot and pointing out each other's flaws and shortcomings, but they both know that they need each other and when Cassius hears of Portia's death, he immediately apologizes to Brutus and realizes that he went too far. They may fight, but in the end they know that they are stuck with each other and they are in the long-haul together.