WARNING: The following contains spoilers for Immortal Hulk #34 by Al Ewing, Butch Guice, Tom Palmer, Paul Mounts and VC's Cory Petit, on sale now.
The One-Below-All has been setting itself up as the most powerful and dangerous force in the entire Marvel Universe, especially given the plans it has for the Hulk and the end of not only this universe but the next. Now, it looks like another Hulk might be involved as well, thanks to of the Mad Titan, Thanos.
As Immortal Hulk #34 reveals, the Leader now believes that She-Hulk actually died in her battle with Thanos before the events of Civil War II, which means she might have a connection with the One-Below-All that she doesn't realize.
WHAT HAPPENED TO SHE-HULK?
When the Inhuman Ulysses Cain gained the ability to see into the future, he was able to assist major heroes and alert them to coming threats. Despite the controversy of changing the timeline by doing so, some heroes saw it as a chance to save the world from tragedies before they occurred. One such opportunity came when Thanos assault a facility looking for a Cosmic Cube. A number of heroes were able to respond quickly to his presence, including She-Hulk. Although the heroes successfully defeated and captured Thanos, War Machine was killed and She-Hulk was put into a coma in Brian Michael Bendis and David Marquez's Civil War II #1.
She remained this way for much of Civil War II and missed the death of her cousin, the Hulk, at the hand of her longtime Avengers teammate Hawkeye. When Jennifer finally woke, she found herself dealing with new levels of inner pain. She briefly could only transform into a savage Grey Hulk form, before getting enough control to regain her Green Hulk form, albeit as a less restrained and controllable form than she's been in the past. She's since been serving as an Avenger and in a relationship with Thor, but her transformations have been more violent and destructive. But there may be something more to her current transformation, especially if the new theory from the Leader is correct.
THE LEADER'S NEW HYPOTHESIS
Immortal Hulk #34 recounts the journal entries of the Leader, and his own encounters with death. As a gamma-empowered person, his (numerous) trips to the afterlife included encounters with the titanic and mysterious One-Below-All. For a period, Leader was convinced that he was being restored to life through his own will-power and mental strength, But he had a moment of clarity when his actions created Soul Man, who was capable of bringing souls back from the afterlife after being bombarded with gamma radiation. One of the times Leader died, he found himself fully facing the One-Below-All once again and coming to terms with it, even growing to respect it.
His studies into death and the green energy that comes from the One-Below-All lead him to theorize that She-Hulk actually died when she encountered Thanos. He also suggests she may not have realized it though, having repressed whatever experience she had in the afterlife when she returned. Leader specifically wonders what would happen if she died again or even if she killed someone else. The idea that Thanos actually killed She-Hulk carries a lot of potential ramifications, not just for Jennifer but for all her allies and the greater Marvel Universe as a whole.
It means that She-Hulk may have encountered the One-Below-All and been affected by it. This interaction could have been responsible for the chance in She-Hulk's attitude and savagery. It was a ferocity that Devil Hulk pointed out to She-Hulk when they fought in Immortal Hulk #7, comparing her new form to himself. It would make sense for She-Hulk to have come back from the afterlife changed if that is indeed what happened to her. The upcoming Immortal She-Hulk one-shot might make that more prevalent, and it's possible that connection will become more explicit soon. If the Leader is right, then Jennifer might be far more important to the plans of the One-Below-All than anyone anticipated, or she could turn out to be the secret weapon that could help stop its machinations.