Sigma pirating grounds, cardamine and the sabotage of the Hispania (of which they blame each other). Corsairs bear a grudge against Outcasts that comes partly from cardamine addiction and partly from the fact that the Outcasts got the fertile planet while the Corsairs got the lifeless rock. Outcasts on the other hand have a smug sense of superiority owing to their slightly above average physical abilities as a result of cardamine addiction, and also the desire to control Sirius through their supply of cardamine - which they know the Corsairs don't want to happen as it interferes with their sense of independence and pride. Add to that reinterpretation of facts between the two over what actually happened on the Hispania, and you got yourself a feud.
But in the end it's basically more or less a turf war. Disco escalated it due to the players though, and it ended up being far too overplayed.
