Since M-Day, Beast is no closer to finding a “cure for the loss of the mutant gene”. He comes to a decision to “consult” with Dark Beast, a version of himself from “an alternate dimension where Apocalypse ruled the Earth”.
Beast consumes a concoction given to him by Dark Beast which will allow Beast to gain access to Dark Beast’s memories in an instant.
One of Dark Beast’s test subjects is Jean Grey of the resistance. In this “memory track”, Prelate Summers has come to check on Dark Beast. Dark Beast tells Summers that Jean’s mutation is in a different “category” altogether, and he intends to “culture some of her nerve tissue” and create more “unique” mutants like her. Thus Nate Grey was created.
But in Beast’s reality, both Jean and Nate Grey are dead. Jean was murdered by Magneto, while Nate “dispersed his being and his consciousness into every living thing on Earth”. Dark Beast suggests that they “[retrieve] and [reconstitute]” Nate Grey.