Madelyne

At the conclusion of Inferno, Jean and Madelyne confronted each other, with Madelyne attempting to mind meld with Jean and kill them both.

Jean manages to survive only by absorbing the remnant of the Phoenix Force housed within Madelyne, giving her both Madelyne's memories and the Phoenix's memories from "The Dark Phoenix Saga".

Jean only managed to survive by absorbing the remnants of the Phoenix Force housed within Madelyne, giving her both Madelyne's memories and the Phoenix's memories from The Dark Phoenix Saga.

Though Jean encourages Cyclops to return to Madelyne, he finds their house abandoned and assumes that Madelyne has left him and taken their infant son; Cyclops returns to X-Factor and he and Jean continue their relationship.

Of course, that closure was destroyed in the Krakoa Era, after Madelyne's return, and his culpability in her death at that point, broke him even more.

Driven mad, Madelyne takes part in a demonic invasion of New York but gives her life to stop Sinister.

Alex admitted as much to Madelyne when he said he as tired of always hearing her talk about Scott when he was right there, ready to accept her.

Genosha's operations were temporarily disrupted by the X-Men, following the kidnapping of Madelyne Pryor.

So Claremont began a major retcon, gradually revealing Madelyne Pryor had actually been a clone of Jean Grey, created by the ruthless and manipulative Mr. Sinister.

Nathan Summers was born to Scott Summers (Cyclops) and Madelyne Pryor, AKA Jean Grey’s evil clone, because comics.

He intended Madelyne only to look like Jean by complete coincidence and exist as a means for Cyclops to move on with his life and be written out of the X-Men franchise, part of what he believed to be a natural progression for any member of the team.

Jean learns that Cyclops has romantically moved on with Madelyne, who is angered over his decision to lead X-Factor and neglect his family.

Madelyne resurfaced, now nearly insane and with powers awakened by a demonic pact, calling herself the Goblyn Queen.

Manipulated by demons and tormented by Scott's rejection of her, Madelyne kills herself in a suicide attack on X-Factor.

Named " Madelyne Pryor ", the unaware clone meets Cyclops in a situation engineered by Sinister and the two fall in love, marry, and have a child, Nathan Christopher Summers.

Storm strikes a deal for Rachels freedom allowing Madelyne and Selene to walk free.

The Phoenix Sword as it was called was guarded and wielded by the sorceress Madelyne Pyre, who inherited the sword from her mother.