Superheroes get called into a huge range of surprising situations as part of their profession. An average day might involve tackling a bank robber, but it could also mean visiting a parallel dimension, fighting your own clone, or being asked to save the "life" of death itself. That's the mission that was given to Jane Foster, the current Valkyrie and former Thor, in the Valkyrie: Jane Foster story "Strange Aeons," which saved the Earth from a terrible fate brought about by the Hulk and the X-Men.
Written by Al Ewing and Jason Aaron, with art by Pere Perez, Valkyrie: Jane Foster #7-8 is a deceptively consequential tale that draws characters from disparate parts of Marvel canon and reveals a startling truth about one of Marvel's most dangerous potential futures, and exactly how dangerous Marvel's heroes are to the natural order of their universe.
The Death of Death
At work as a morgue assistant - a job befitting her recently acquired responsibilities as guardian of the dead - Jane is attacked by a corpse which informs her that Death itself is dying, imploring her to gather a team to help. Of course, Jane is a medical practitioner, so her first thought isn't to gather a super-team, but rather a medical team uniquely suited to prevent the passing of Death itself. Gathering together Doctor Strange, Night Nurse, Excalibur, Cardiac, and Manikin - Marvel's super-doctors - Valkyrie passes through into Death's Realm, not suspecting that not all of her team are on board for guaranteeing Death's survival.
Initially attacked by undead "antibodies," the team eventually confront the disease actually killing Death, which Excalibur (aka Doctor Faiza Hussain) is able to hold at bay while Jane journeys on. Sadly, Jane is hampered by Cardiac, since the antihero believes that they should allow Death to perish, preventing any more humans from passing away. Cardiac only comes to his senses after seemingly killing Manikin, but Valkyrie is shaken by a sentiment she already believes to be true.
Ultimately, Valkyrie makes it to the Death of Death; a vast, cosmic entity who is behind Death's ailment. Somewhat surprisingly, however, it's revealed that the Death of Death isn't an unnatural attacker, but rather an expression of the Living Tribunal - Marvel's embodiment of the guiding force behind their reality. Just as the Living Tribunal once asked She-Hulk to make a legal case for not replacing the mainstream Marvel Universe with the neater, more modern Ultimate Universe, it asks Jane Foster's medical opinion: should Death really be allowed to continue? Jane's answer is persuasive, but before she gives it, the Living Tribunal reveals the truth of the situation, implicating Marvel's heroes in this reality-altering dilemma.
Marvel's Heroes Are Killing Death
It turns out that rather than Death having been struck down by an outside disease, the ailment is a supernatural expression of a very normal imbalance in the natural order. In expressing itself as the Death of Death, the Living Tribunal is making a sincere offer to eradicate death in the Marvel Universe. Again, this isn't the work of some godlike force interfering with reality, but rather the spiritual expression of an actual question facing Marvel's heroes - in a world where so many heroes have returned to life, is there any point having death in the first place? The Death of Death explains:
I am what your mind can grasp. I am a point of decision. A Green Door swings open, and Death is irrelevant. A pod grows new life, and Death is without meaning. So many have returned from death. More and more. Even you. So Death grows weaker... sicker... Until the question must be asked. Do we need Death? Any Death? Convince me.
The mentions of the Green Door and the life-growing pods are what involve the Hulk and the X-Men. Recently, in The Immortal Hulk (also by Al Ewing), it's been discovered that gamma radiation gives humans the ability to move through the "Green Door," effectively making them able to return from death as an act of will. Meanwhile, the mutant nation of Krakoa has developed a process of resurrection in which golden eggs are used to hatch reborn mutants. In this way, many corners of the Marvel Universe have done away with death so completely that it has unbalanced the underpinning forces of reality. In surpassing death, the X-Men and the Hulk (along with Marvel's many other heroes who have returned from apparent death) have been pushing against the natural order, and the balance is finally tipping.
A New Cancerverse
Jane admits that she agrees with Cardiac - the world would be better if humans lived on - but reasoning that Death represents all death, she argues that unlimited growth on every level would be unsustainable; indeed, as a doctor she can only see limitless growth as a kind of cancer. The Death of Death agrees with her assessment, consenting to spare Death and allow her to continue to take human life. Thanos' beloved Death arises anew, but something she says adds new context to this decision: "I am healed. It has been decided. The process of death will continue. This plane will not transition to a Cancerverse."
The bombshell that Earth would have become a Cancerverse is huge news about the disaster Valkyrie just averted. Explored in 2010's Realm of Kings, the Cancerverse was previously thought to be an adjacent dimension devoid of death. Within it, Lovecraftian forces had taken over warped and deformed versions of Marvel's heroes, creating monstrous enemies set on spreading out into the mainstream Marvel Universe. Deeply evil and unkillable within the Cancerverse, these perverse heroes were cancer made flesh - forever spreading and devouring all that is good. The Cancerverse was eventually sealed away, but it took the concerted effort of multiple alien civilizations and universal forces such as Galactus. The events of Valkyrie: Jane Foster reveal that the Cancerverse isn't just the name of one reality, but rather a potential end result of any reality where death is banished.
In saving Death, Jane Foster saved Earth from a literal hell marked by endless suffering and ceaseless expansion, recontextualizing the Cancerverse as something much bigger than it first seemed. Many Marvel characters are concerned with Death's "survival" - Thanos himself was once trapped in the Cancerverse along with Marvel hero Nova, and may look kindly on Valkyrie for saving his beloved - and it's possible that this abstract entity may even owe Jane Foster a favor in the future, suggesting that this story will likely reverberate for some time.
Even more importantly, however, "Strange Aeons" acts as confirmation that Marvel's superheroes are always a lot closer than they may think to drastically changing the natural order. Without knowing it, the X-Men and the Hulk almost enveloped Earth in its worst-case scenario. Here's hoping that the next time a well-meaning hero pushes against the boundaries of what's possible, there's a doctor on call who's as able to help as Jane Foster, aka Valkyrie, was on this occasion.