The following contains major spoilers for Sins of Sinister #1, on sale now from Marvel Comics.
Ever since the X-Men entered the Krakoa era, they've faced a constant fate for the survival of their species. Whether the battle is against Orchis, Moira McTaggert, or even people they thought were allies, there's always a war against their right to thrive. But one element has shown just how unprepared the mutants are, thanks to Mister Sinister and his ability to get the drop on all of Krakoa. That said, one particular member of the team has gotten the worst of Sinister's grand plan and it may lead to him dealing with a much deeper ailment.
Sins of Sinister #1 (by Kieron Gillen, Lucas Werneck, Geoffrey Shaw, Marco Checchetto, Juan José Ryp, David Baldeón, Travel Foreman, Carlos Gómez, Federico Vicentini, David Lopez, Joshua Cassara, Stefano Caselli, and VC's Clayton Cowles) explores the execution of Mister Sinister's plan to rule Krakoa and eventually the world. After killing the Quiet Council's strongest mutants, Sinister used the chance to replace them with his own clones. In doing so, he used the clones to spread his influence worldwide, and those who died were resurrected as his minions. Unfortunately, those that failed to comply suffered a worse fate, such as Nightcrawler, who became something scarier. But his change may allude to a larger issue that turned him into a monster once before.
Nightcrawler Was Previously Remade Into a Monster
In Sins of Sinister #1, Storm caught wind of the betrayal in the Quiet Council and immediately went against the plan. But when she demanded to speak to at least one ally, Sinister walked up with the real Nightcrawler. But rather than the three-fingered friend she knew, Kurt had become a feral animal that resembled a dog-like demon. According to Sinister, this was because there was something wrong with his genes that he had yet to figure out.
During the reality-altering Secret Wars, 2015's Inferno #1 (by Dennis Hopeless and Javier Garron) saw Magik take over Limbo and use it to take over the world. In doing so, she turned Nightcrawler into a dragon that did her bidding. But the transformation also tore apart his soul and left him a shell of the person he once was. Kurt could still teleport as a monster but did so to devour all those that opposed him and became a mount for Magik and the Goblin Queen.
Magic May Have Affected Nightcrawler's Mutation?
The effects of Inferno, while erased and replaced with a new world, were still prevalent in the Marvel universe. As a result, there could still be latent effects from what happened during the 2015 Secret Wars event. In the case of Kurt Wagner, the failed results of Sinister's experimentation may have nothing to do with science but everything to do with magic.
Since his soul was ripped apart and his body changed into something unholy, the trauma and residual magic may have affected his body and mind. Because of this, should he ever be modified or altered against his will again, a monster would arise. While Sinister has claimed that he could fix it, that remains to be seen as the cause of Kurt's problem could potentially never be sorted by science and may take on a more dangerous form in the future if left unchecked.