In GoW Chains of Olympus, when the Fire Steeds approach the realm of Hades they disappear and it's said that those being of light weren't welcome in that place.
So (I believe) Helios' power had no influence over the realm of Hades, which means (if I'm correct) that the god Hades wouldn't be affected by the deep slumber caused by Helios' absence that affected the other gods.
It's also said that Kratos could see the bright of Helios at great distance, when in the depths of Hades. And that makes me think that Hades was aware that Atlas was released but he didn't do anything about it.
Why didn't Hades help to stop Atlas? Considering that the destruction of the World was not his desire (because he had no reason for that)? Please, I'm looking for sourced answers.