Lois London was born to Katherine (later changed her name to Barbara) London, a music teacher, and Nick Brown. It's assumed that she experienced a normal childhood with her mother and father. In her teenage years, she found out that her mother had been previously married to lawyer Carter Blaire, and that she has a half-sister, Alison Blaire. Surprised by this, Lois attended her sister's performance at Carnegie Hall. Lois and the rest of her family worked out their differences.
Curious as to how her sister was, Lois decided to get to know Alison. The two bonded from the start. Though she accepted Alison's mutation, she found being a mutant dangerous as they were attacked by Mystique, Rogue, and their Brotherhood of Evil Mutants. Lois's life was once endangered by Rogue, but was saved by her sister. Over the following weeks, Lois suffered various headaches and even fainted a few times. Finally, as she took a walk to get some air while Alison performed in a club, Lois was attacked by a would-be mugger. She panicked, her hand started to glow, and the mugger died, revealing that Lois was a mutant as well. Lois went to Dazzler for help and Ali, with memories of her own murder trial still fresh, didn't think Lois would be treated fairly. The sisters decided to hit the road and travel to California. As people kept recognizing Ali, she disguised herself with a black wig. However, they were still followed, as someone blackmailed them with photos of Lois and the mugger. The photos had a phone number attached to them. They called the number and were told that Lois and her sister had to break into a certain house and kill the man sleeping inside. 
At night, they broke into the house and, after a short fight, it turned out that the owner was Nick Brown, Lois' father. After becoming a successful agent and financier, he had been paying his butler to track down Lois. The butler witnessed the death of the mugger and it was he who had blackmailed the sisters into trying to kill his master, as he wanted to steal Brown’s fortune. Thanks to Angel's timely arrival, the crime was prevented and, with the pictures, Lois was easily cleared of all charges. They showed that she was actually defending herself and, fortunately, the crackling aura of energy was not even seen in the photos. Lois' father showered the two sisters with riches, buying gifts for Lois and getting Alison gigs at important events. After discovering that her stepfather had purposefully put her in danger to generate publicity, Alison became angry and decided to leave her stepfather once and for all. Alison thought that Lois would leave as well, but Lois felt that she needed somebody to protect her and Nick seemed the best choice. 
Over the years, Lois had grown more bitter and resentful of Alison, and was haunted by killing the homeless man. Nick was an alcoholic and took his drunken rages out on Lois. One day in his office, he berated Lois for destroying his family and slapped her, and Lois put her hand out to his chest, stopping his heart and killing him. As he died, her father told her he loved her. Selene, initially disguised as Nick's secretary Claudia, came in and reassured her, saying that death was her gift - Selene then revealed herself and recruited Mortis to her Inner Circle.
In a final battle Mortis fought with Wolfsbane and was critically wounded by her. Following Selene's death at the hands of X-Force, Blink teleported Mortis away, making them the only two members of the Inner Circle who escaped the remains of Genosha.
Lois recuperated and then hired Arcade and Klaw to kill Dazzler. When Dazzler fought through Arcade's Murderworld, Lois confronted her directly, only to find out that her death touch was useless on her own sister. Dazzler knocked Lois out and took her into captivity on Utopia. She was placed into a psychically induced coma by Psylocke who volunteered to help her undo the psychological damage of her past and her brainwashing by Selene.
Molecular Disruption Field:
- Infinitesimal Disturbance: She can generate a highly-destructive energy from her being which, through molecular transformation, can disintegrate or liquefy inorganic matter or cause living things to disperse their life-energies, either causing temporary bouts of pain and weakness or instant death.
- Blast Power: She can discharge her energy field as deadly force waves.
- Death Touch: Her power also works on a tactile level being able to transfer the fatal abilities of her energy wave by skin to skin contact; for most people so much as a glancing touch can be instantly lethal.
- Levitation: When surrounded by her energies Mortis gains some limited form of aerial elevation.
- Light Projection: In contrast to Dazzler's luminously radiant abilities Mortis generates a dark photonic aura around herself which often accompanies in conjunction with whenever she uses her power.
- 18 appearance(s) of Lois London (Earth-616)
- 3 appearance(s) in handbook(s) of Lois London (Earth-616)
- 1 mention(s) of Lois London (Earth-616)
- 1 mention(s) in handbook(s) of Lois London (Earth-616)
- 9 image(s) of Lois London (Earth-616)