WARNING: The following contains spoilers for Fantastic Four #27 ahead!
It took the best of DC's Justice League to bring down The Batman Who Laughs. But even after his defeat, this terrifying entity has returned as a reality-warping, possibly universe-destroying nightmare called, "The Darkest Knight." While it seems as though it will once again take everyone the Justice League has to stop him once more, Marvel's Fantastic Four will face their own "Darkest Knight," all on their lonesome - which is pretty typical for Marvel's first family, in all honestly.
The Griever at the End of All Things claims to be the living embodiment for the heat death of the universe - and the incarnation of the second law of thermodynamics. With a level of strength possibly surpassing Marvel's most powerful cosmic entities, the Griever has declared a personal vendetta against the Fantastic Four and the Future Foundation. Namely, for the slight of rebuilding the multiverse after the events of the Secret Wars storyline, which saw the Marvel Multiverse combined into one prime universe. For something like the Griever, the audaciousness of repopulating the Multiverse was like undoing unfathomable eons of work.
Even Franklin Richards, the son of Reed and Sue, once a powerful cosmic being in his own right and now de-powered, donned an FF-colored Iron Man suit and took the Griever head-on. The act, in true Fantastic Four fashion, was a ruse designed to catch and hold the Griever within the Baxter Building as Reed sealed it within its own dimension and then promptly deleted the entire building, and the Griever with it. But even then, it wasn't enough to truly destroy her.
With the Griever returning once more, there will likely be another cosmic event similar to when they first fought the likes of Galactus so many decades ago. This time, the stakes will be the fate of not just their universe but for all universes that will exist. And once more, while it will take the Justice League to face down the Darkest Knight, for the Fantastic Four it'll be one family against a literal god.
