Peter was completely lost and understood almost nothing. Although he had no interest in mysticism, he still wanted to know what was going on. Why were there two Constantines? What was their relationship? What were they both discussing with Dr. Sohip?
Peter certainly could not figure it out himself, but he knew he had a powerful helper. So he returned before that black sun and asked his question in the most devout manner possible.
Soon, another enormous mass of knowledge was crammed into his mind. Peter sighed painfully, sat on the ground, and struggled to digest the complicated mystical knowledge.
When he had read through most of it, he realized that all this knowledge was about John Constantine.
Constantine was special.
That was what all the material was trying to convey. As for why, it probably had to begin with the grudge between Heaven and Hell.
In short, the countless universes in Constantine's world shared the same Heaven and Hell. Their struggle for followers in the human world did not take place in only one universe, but across all universes simultaneously.
But due to certain factors, Heaven and Hell could not turn the human world into a battlefield for hot war. Still, their cold war had never ceased: wars of faith, information wars, and countless proxy wars of every scale.
This had continued for a long time, until one day, the Archangels of Heaven and the Demon Kings of Hell decided they could not go on like this. They should sit down and talk, competing in a more civilized and fair manner.
That method was Constantine.
Constantine himself was a black box used for gambling. His soul had been granted special permissions. No Demon King of Heaven or Hell could open the box to inspect the composition of the power