Within the worlds of Marvel and DC, the heroes of each respective Earth have recently been embroiled in battles that have ravaged and changed the cosmic landscape of their universes. In Marvel's Empyre, the Avengers and Fantastic Four faced an invasion of the Cotati, while also witnessing the rise of a new emperor and alliance that resolved centuries of war. On a larger scale, the Justice League has lost their multiverse to the power of Perpetua and the Darkest Knight within the course of Dark Nights: Death Metal. As their universes have suffered massive changes, both have also seen the return their universal observers.
The Watcher has always stood at the center of monumental events that have shifted the direction of the Marvel universe. That came to an end however, following the onset of Original Sin, when Uatu was murdered by the senior Nick Fury and his eyes were stolen in an attempt to utilize his many secrets. For his actions, Fury was sentenced to become the Unseen, forced to only watch the events of the universe continue without being able to interfere. After the Cotati's surrender, Empyre: Fallout Fantastic Four, written by Dan Slott and drawn by Sean Izaakse, revealed that their weaponry had not come from the Cotati's own reserve, but had emerged elsewhere.
Trying to learn of their origin, the Unseen used his power to search for the weapons' history. Instead, Uatu emerged from Fury's eye, still missing one of his eyes and declaring that there shall be a reckoning to come. After his return, Uatu used his powers to search through Fury's memories and learned of all the events that he had missed in his absence. In particular, he saw the origin of the Cotati's weapons which seem to promise the return of what he called, "the First War". Additionally, Uatu saw the scheming of his fellow Watchers and decided he would also use his power freely, starting with the appointment of Nick Fury Sr. as his herald and Unseen Hand.
Over in the DC universe, back in 2015, Metron, serving in his role of an observer from the New Gods, freely moved around the multiverse and observed the actions of cosmic beings. His end came when both he and Owlman came too close to the secret truth of the New 52 and were killed by Dr. Manhattan, who was intent on keeping his presence and interference hidden. Years later, as the multiverse lay in ruins, Death Metal: Rise of the New God, from James Tynion IV and Jesus Merino, introduces the character and role of the Chronicler, a being from the omniverse that has set out to watch the end of this multiverse.
As Perpetua clashes with her former servant, the Chronicler travels to interview certain beings that he believes can show him the path that led to the heroes of this world's end that is soon to come. When he finds the likes of the Joker and Psycho-Pirate to be unsuitable storytellers, the Chronicler makes the decision to travel to the Moon and to reanimate the bones of Metron, who has seen this story from its origin. After learning of the current state of his world, Metron hands the Chronicler a book of his own making: one that tells the story of this multiverse from its beginning to its near-end. Upon reading it, the Chronicler comes to believe in the heroes of this world and, like Metron, wants to restore their world.
Having been missing for the last few years, both of these observers have found their realms changed and under threat of an unsure future. In the past, these beings would have stood by, merely watching and recording the exploits of their universe's heroes. Now, however, it seems that both Uatu and Metron will have major roles to play in the coming battles that will define the cosmic storyline of each universe.