WARNING: The following contains spoilers for X-Factor #7 by Leah Williams, David Baldeon, Israel Silva & VC's Joe Caramagna, on sale now.
A huge mystery just broke open in the pages of X-Factor, as the team was secretly investigating the death of Siryn. X-Factor's job is to figure out the cause of death of any given mutant before they're allowed to return through the resurrection protocol.
They ended up investigating a second Siryn death, which caused them to look hard into what was going on with the mutant. And even though Theresa Cassidy and her dad Banshee are one of the closer families within the X-Men, he had no idea that she had been dying.
For years, Sean had no idea that he had a daughter, as his cousin, Black Tom Cassidy, raised her as his own after her mother died. After Tom was arrested, he let Sean know he had a daughter, and the two were reunited. This makes the notion that Sean had no idea she died a genuinely shocking moment.
Northstar and Prodigy teamed up to interview Banshee about Siryn. When he seemed unaware that she has been acting strange, Prodigy mentioned that she had died a lot recently. That was a complete shock to Banshee, which Northstar realized meant he would be of no help to them. It seemed unusual that her own father would have no idea that his daughter had recently died and been resurrected more than once. However, that could be because she was possessed by Morrigan, the goddess of death and battle.
There could be more to it than that. Before Krakoa existed, Banshee died more than once trying to save lives. The first was because his power levels were deficient after he had his throat cut by Mystique. After his death, Cyclops let Siryn know her father had died a hero and gave her a videotape. On the tape, Banshee said he hoped he did more good than bad in his life and was ready to be with her mother in Heaven. Siryn refused to believe he was dead but finally came to peace with it and took on the name Banshee for herself. Sean ended up returning to life but died again while battling O*N*E, leaving Siryn to experience the grief all over again.
Banshee was brought back again when the X-Men formed their new nation on Krakoa, and was one of the earliest resurrections that took place on the island. His previous injuries were healed with his resurrection into a new body, particularly the throat injury that limited his powers. He was back to normal, and he once again reunited with Siryn.
But while he was gone, something happened to Siryn. Polaris was dying, and Siryn called upon the Morrigan for help. When she learned the death god Morrigan would save Polaris only if she would become the new Morrigan, Siryn accepted. She killed the Morrigan and became the new Morrigan. With that said, when she ended up on Krakoa, it seemed she was finally free of the Morrigan's will.
Siryn and Banshee met up on Krakoa, reuniting after his resurrection and celebrating the new mutant nation's formation. The two were apart for so long, but they seemed to be reunited again, with Siryn coming to his defense when Banshee was injured by Amneth's forces. However, it turned out that Morrigan was still in control.
While Banshee and Siryn have gone through a lot, there is a good chance her father was kept in the dark about his daughter because Morrigan didn't want anyone to notice a change in her charge. It is also possible that, somewhere deep inside, Siryn wanted to protect her father. Siryn has died more than once, possibly trying to kill the curse, but she has failed, and now Morrigan may have X-Factor right where she wants them.