The Dark Mother was the leader of a secret organization known as the Dark Sisterhood, the Dark Mother ruled with an iron hand, and was willing to do anything to further her aims, no matter how it affected others.
The Dark Sisterhood was formed long ago when women born with unusual powers began banding together for protection when they were branded as witches. The group adopted the name of the Dark Sisterhood in defiance of their persecutors. They sought power to save themselves from death and torture but over time their goals became more sinister. Rather than seeking equality they decided to rule by replacing a corrupt system with one of their own design.
Today the Sisterhood use their mutant psionic abilities to manipulate crucial figures in every level of society from large crime cartels, police chiefs, corporate CEO's and even heads of state to further their goal of global domination.
The Dark Mother was a powerful mutant precog and telekinetic using the alias Finality. She appeared to have adopted these morals for herself, she approached Cable's mentor Blaquesmith seeking his help believing that the Sisterhood's aims were one with that of the Askani, Blaquesmith aided them by arming them with psimitars.
When the group became aware of the time anomalies Cable and Rachel Summers, the Dark Mother ordered them, and any who stood by them, killed. A band of twenty members of the Dark Sisterhood attacked Cable's Hell's Kitchen safehouse but he defeated them and destroyed the base.
Cable set about stopping the Dark Sisterhood from installing one of their members as the next President of the United States. During the final battle with Dark Mother, Cable regressed her mind and the minds of the remainder of the Dark Sisterhood to that of an infant.
After the events of M-Day Mister Sinister ordered the Marauders and the Acolytes to kill all known precognitives, and to collect all of the mutant Destiny's diaries which contained information on the future. From the information that Emma Frost took from the Marauders' minds during battle, they were successful in killing Dark Mother.