WARNING: The following article contains spoilers for Thor #21 by Donny Cates, Nick Klein, Matt Wilson, and VC's Joe Sabino, on sale now from Marvel Comics.
For years, being able to wield Thor's enchanted hammer Mjolnir has been viewed as one of the highest honors that a hero in the Marvel Universe can achieve. Thanks to a series of powerful magic runes, only those "worthy of the power of the Thor" are capable of even lifting the hammer off the ground, and it was long believed that these enchantments were referring to those who shared Thor's innate nobility and courage. Despite their abundance within the Marvel universe, only a select few heroes have managed to lift Mjolnir, including Jane Foster and Captain America, who famously wielded the hammer against Thanos during the climax of 2019's Avengers: Endgame
Unfortunately, Thor #21 revealed that Mjolnir itself has always had a very different definition of what it means to be "worthy" of its power, and the rogue weapon's revelation casts a sinister shadow over all of the moments that heroes wielded it for good. Mjolnir's twisted definition of "worthiness" revealed that those who've wielded it may have been driven by something much darker than heroism.
From the beginning, the ongoing Thor series has put a spotlight on the newly-crowned king of Asgard's deteriorating relationship with Mjolnir. Throughout the series, Thor's once-unbreakable bond with his iconic weapon has been showing cracks, culminating in the increasingly-rebellious Mjolnir attacking Captain America completely unprovoked. Following this incident, Thor left the hammer in the Avengers' care, only for the weapon to suddenly vanish without a trace. Thor's research into this phenomenon led him to a prophecy centered around the "God of Hammers" a being destined to kill the king of Asgard and destroy the Ten Realms. Soon after, Thor and his estranged father Odin investigated a series of brutal massacres being committed across the Ten Realms that eventually led them to Earth, where Thor was confronted by Mjolnir itself in the form of a monstrous being made of pure electricity.
Claiming full responsibility for the atrocities that Thor witnessed, Mjolnir brutally beat their former wielder to within an inch of his life, peppering each attack with sadistic insults. After Odin was crippled in an attempt to protect his son from a lethal blow, an enraged Thor demanded to know why Mjolnir was doing this. The hammer revealed that they've grown tired of being used as a weapon of justice. Claiming that Thor and all of its other wielders never really understood the true meaning of its enchantment, Mjolnir bluntly stated that to be "worthy" of its power is to crave destruction and that they've simply grown tired of Thor's peaceful approach to ruling Asgard.
The reveal that the ability to wield Mjolnir was never linked to the pureness of one's heart was a crushing revelation that casts Thor's entire history with his hammer in a much darker light. Since the moment Thor was first gifted Mjolnir, he'd dedicated his entire life to proving that he was worthy of it. He built his entire persona around the idealized warrior that he believed he had to be to wield it. Through Thor, Mjolnir has played a major role in the downfall of some of the most powerful supervillains in the Marvel Universe. The revelation that the ability to wield it was fueled by the wielder's lust for violence and not the desire to protect the innocent implies that, deep down, the power that Thor wielded whenever he used Mjolnir may have come from his desire to hurt his enemies.
This carries over into the times that other heroes wielded Mjolnir, as well. Looking back, one could make a strong argument that it was the worst part of them that made every hero who's wielded Mjolnir worthy of doing so. Beta Ray Bill, Mjolnirs first alternative wielder, had just lost his entire homeworld to the cruelty of Surtur, and the anger he felt for the loss of his homeworld would have made him worthy in Mjolnir's eyes. The same could also be true for Captain America, who's wielded Mjolnir against enemies who'd threatened the safety of his loved ones and country during the climaxes of the Fear Itself and Secret Empire crossover events. Even Chris Evans' Captain America could have been seen as worthy due to the hatred he felt towards Thanos if the Marvel Cinematic Universe's version of Mjolnir feels the same as its comic book counterpart.
Despite its reputation as a symbol of heroism, Mjolnir has fully embraced its supposed destiny as the God of Hammers, and its newly-revealed lust for destruction implies that this may have been the fate it's always wanted. No matter what those who wielded it may have believed, it seems that Mjolnir may have been happier if it'd been used by the villains.