So far we've only seen Geras' blood being blue. But at the same time Geras also has weird patterns all over his body, which makes him look like he has been pieced together. So maybe Geras is just Kronikas creation, yet is still powerful enough to a point, where he doesn't seem to be afraid of Raiden, who is a god.
So Kronika might also end up bleeding red, just like Shinnok. And she is very, very likely an Elder God, since regular gods shouldn't really have the power to do what she does... and what she allows Geras to do.
