Main characters: Wolverine, Storm, Phoenix, Havok, Colossus, Iceman, Shadowcat
Villains: Apocalypse, Mr. Sinister
Secondary characters: Rogue, Gambit, Angel, Xavier, Magneto
Plot overview:
For decades, Apocalypse has been manipulating everything, preparing for the day when mutants constitute a large enough population that he can begin his eugenics war - mutant vs. human, survival of the fittest. He was born in the 30th century BC, and is effectively immortal. He has some shape changing abilities, and limited telepathy.
He saw to the formation of the Weapon X program to create stronger, deadlier mutants for his coming war. He subtly pushed Magneto into attempting to artificially spike the mutant population of the world (but that was doomed to failure regardless - the device wasn't yet ready). He helped stir mutant and anti-mutant fervor during the "cure" debacle, the better to ignite the war he seeks. The agent of his agenda is Mr. Sinister. Assisting Sinister is a young thief named Remy LeBeau, who befriends Rogue after she leaves Xavier's School.
But now Phoenix arrives, a traveler from the future, who seeks to stop Apocalypse, and prevent the hell on Earth he has in store. Xavier has returned from the grave, thanks to telepathically sending his mind into a healthy, albeit soulless, body. And this new Phoenix claims to be the yet-unborn daughter of two X-Men believed dead. Magneto's powers are beginning to return, something that Erik is pushing on a daily basis.
Phoenix leads the X-Men on an assault against Mr. Sinister and his Reavers, who are led by Gambit. In the melee, Rogue is knocked unconscious. While carrying her to safety, one of the Reavers, Carol, is in skin-to-skin contact with Rogue when her powers return. With both now unconscious, the connection can't be broken. Carol dies, and Rogue permanently absorbs her memories and powers - flight, strength, and invulnerability. Gambit and the X-Men find Rogue and Carol's body, and the quickly realize what has happened. A truce is called by Gambit, who cares more for Rogue than for his employer, Sinister. Gambit goes back to the mansion with the X-Men, and is told what Sinister has been doing. Gambit, who had no idea, vows never to work for Sinister again.
The X-Men track down Apocalypse's hiding place. When they strike, they find Apocalypse is ready for them. The battle is fierce, and when all hope seems lost... Scott and Jean arrive to save the day. Apocalypse is routed, and his plans have been smashed. He escapes, vowing that this is merely a delay.
Bewildered by Scott and Jean's resurrection, they discover that the body occupied by Dark Phoenix was, in fact, created by the entity from surrounding matter and telekinetically reorganized on the cellular level into a perfect duplicate of Jean's body. It psychically split from her, and she no longer suffers from the multiple personality disorder caused by Xavier's mental blocks.
Meanwhile, Jean was still within the telekinetic bubble she and Dark Phoenix created when the waters of the lake threatened to crush her. She was conscious enough to psychically protect Scott's mind when his body was destroyed by Dark Phoenix, and used the same method to create a new body for him, effectively restoring him to life. When Dark Phoenix was killed, she was able to break free of the telekinetic bubble and return to the surface world.
Rachel can't return to her future, because it no longer exists. She's now trapped in a past that's no longer her own. In this new timeline, it's even possible she may not even be born. Yet, she still exists, a phantom remant of a vanished world.