Why the Karma Meter? Chaos is taking a look as to whether Leo and his descendants will choose the light, will choose the dark, or will choose their own fate.
During the opening of the second game, you see Weiss holding a sword with someone ominous at the background who is pretty much Chaos. At first since Weiss kills Chaos, you get to assume that it is a set up for an epic rivalry between Chaos and Weiss himself. Then you get to The Reveal.