Aaron is (understandably) still butthurt from failing to make his houseSYSTEM successful. And Mark clearly was not only deceiving him but also downright stealing his work. Ultimately though that lack of character doesn't really matter - Mark was obviously more driven and had a clearer vision. I think the only lesson we can learn here is that dedication always wins over talent. And besides: Stealing and building a students directory across universities is one thing, creating a profitable business and amassing 900 Million users is a completely different story (and a task to which zuckerberg had a comparatively small contribution).