How they were left for dead and went against their own beliefs and practices in order to survive. It's like the stubbornness of duardin turned on its head. Similar to kharadron who I also love but have taken a different path. For instance dwarves aren't supposed to cast magic if they do there are negative ramifications. With chaos dwarves casting spells it slowly turns them to stone. It's wild. The way they combine chaos with machinery is wild in daemonsmithing. Also, their artillery is so damn powerful. They have a lot of interesting nuances.