WARNING: The following contains spoilers for Marauders #10 by Gerry Duggan, Stefano Caselli, Edgar Delgado, VC's Cory Petit, and Tom Muller, on sale now.
Of all the X-Men, only Shadowcat has been shown having direct problems with using her powers on the island nation of Krakoa. Even though Kate "Kitty" Pryde has been one of Krakoa's chief agents in the outside world in Marauders and a lengthy history as an X-Man, Pryde reveals that she feels actively unwanted by the X-Men's sentient island home in an e-mail in Marauders #10.
However, Nightcrawler's response to that e-mail seems to have give some more credence to a shocking fan theory that's beginning to seem more plausible. According to this fan theory, Pryde may not even be a mutant at all.
PHASING PROBLEMS
Ever since Krakoa was founded, Shadowcat has stood out among the rest of the mutant race as the only one who has proven incapable of crossing through the Krakoa Gates. The gates are only supposed to be able to be used by mutants, which is what made it so concerning when Shadowcat was unable to pass through them. She was eventually able to sail to the island and be given a home on it, but she's admitted that her powers are acting out of sync every time she's there.
This played a major part in Shadowcat deciding to become the Red Queen for Emma Frost, doing work for the X-Men as the leader of the Marauders and leaving the island she's technically not accepted onto. The question about what could have prevented her from walking through that gate has lingered, which was only compounded when Shadowcat was killed by Sebastian Shaw. She has since also proven to be the only mutant incapable of being brought back by the Five - who were easily able to resurrect powerful figures like Charles Xavier and Apocalypse. This has all led some to wonder why exactly Shadowcat might be immune to the effects of Krakoa and the island.
One persistent fan theory has been that Shadowcat might secretly not actually even be a mutant. This may have even been teased before the birth of the modern Krakoa, during the fallout of Wolverine's brush with death. In Hunt for Wolverine: Adamantium Agenda, a number of Avengers went on a mission to recover a stolen copy of Wolverine's genetic code, which could prove very dangerous in the wrong hands. During that mission, Iron Man got the chance to look through the archives of mutant DNA that had been collected by Mister Sinister and discovered that at least one mutant had been genetically altered to only appear as a mutant. Iron Man even describes the person as a "sleeper agent" within the X-Men. The identity of that X-Man was never exposed, leaving it as a mystery.
But if this "sleeper agent" was Shadowcat, that would explain many of her problems with Krakoa. It would also explain the problems Pryde has been having using her powers on Krakoa at all. In the email she wrote shortly before departing on the mission she would never return from, Pryde mentioned that she was growing increasingly angry and lonely due to Krakoa seemingly singling her out. She even reveals that she can't fully use her phasing powers on the island, as something about the location is messing with her abilities. There could be a specific reason Shadowcat could be targeted. This could be because Krakoa doesn't trust Pryde, or it could be the machinations of a villain like Sebastian Shaw or even the Phalanx.
However, Shadowcat really just isn't supposed to be on Krakoa, and the island is naturally having an effect on the false mutant. It would be a major shift for the character but would explain a lot of the recent irregularities that kept Shadowcat from fully adjusting to the Island nation. If this was true, it could also spell doom for Sebastian Shaw. If Shadowcat had been a mutant, then he'd technically be able to argue that he hasn't broken a cardinal sin of Krakoa. If Shadowcat is indeed not a mutant, then it could be grounds for banishment into the heart of Krakoa alongside Sabertooth for killing a human.
If the idea of Pryde not being a mutant has any validity, it's still not clear who would've modified the long-time X-Man Shadowcat to appear as a mutant and why they might've done so. Krakoa already has plenty of enemies and the X-Men still have a few longtime foes who haven't joined Krakoa yet. While every aspect of Shadowcat's final days and her death seem to be surrounded by far more questions than answers, it's quickly becoming apparent that there was far more to Pryde than anyone -- even herself -- ever really knew.