Marvel's latest Civil War is already splintering the Marvel Universe, but this time around the split is extending to Marvel's merry band of mutants the X-Men.
For mutants, the issue is not a moral one, but one of survival. The terrigen mists are affecting the mutants in a severe way, making them sterile and unable to procreate any new mutants. This could spell extinction for the mutant race, hence why Magneto and his team have taken such a proactive stance against the Inhumans. His team includes Psylocke, M, and Sabretooth.
In Civil War II X-Men #1, the struggle gets more intense, with Storm and her team of Extraordinary X-Men (which includes Jean Grey, Magik, Iceman, Old Man Logan, Cerebra, and Nightcrawler) rushing to the aid of Magneto's team against the mists and multiple sentinels (via CBR). After the dust has settled, it comes to light just how the team found Magneto and his squad, which is credit to Ulysses, the Inhuman who can see visions of the future.
Naturally, Magneto is pretty peeved about all this, and he raises multiple solid points, like the fact that the Inhumans have done nothing to help get rid of the mists, or to help mutants cure the effects. Magneto's X-Men return to their home base, but later are approached by a surprising visitor.
On the last page of the issue, Nightcrawler teleports into their HQ. Magneto goes on to tell him about the severity of the mists, and why his appeals for peace between the two groups will go unfulfilled. Nightcrawler responds: "You misunderstand. Storm didn't send me. I'm here of my own free will...because I think you're right."
It's a pretty major defection, especially for a character that doesn't necessarily enjoy conflict like Nightcrawler. I'll be interested to see where Cullen Bunn takes this, and how Storm and her team will react once they hear the news.