Phoebe Marrs is a businesswoman who spent much of her early life domineered by her own family. At first it was her father Archimedes Marrs, a shrewd and ruthless billionaire, doing the domineering. Phoebe run away from home when 19-years-old. She met a young store owner, Michael Payne, and married him. The marriage only lasted 18 months. Desmond Marrs, her twin brother, discovered them. He orchestrated events which drove Payne's store out of business, leaving Michael a broken man. Desmond then offered his brother-in-law 1 million dollars in exchange for a divorce and his sister returned to him. Michael accepted.
Phoebe kept a secret from the men in her family. She was pregnant when divorced. She settled in Singapore for a while in order to give birth. Edward Payne, her son, was born there and then smuggled to Connecticut, placed in the care of a surrogate family. To her disappointment, Edward was born with a mental condition: he begun each day with no memory of the previous ones. He could never recognize his own mother.
When Archimedes died, Desmond and Phoebe inherited Marrs Corporation and the fortune that went with it. Their inexperience would lead to financial trouble early in their career. They had a determined rival in Tony Stark. Desmond hated the man. The Marrs twins where in time able to restore their company to prosperity. But Desmond grew bored with life and suicidal. Phoebe restored his interest in life by offering him a mystery to solve. Parallel Conglomerate, a minor subsidiary of Marrs, had recently been sold to a "mystery man". Renamed Oracle, Inc it had suddenly become an emerging powerhouse. Who would be able to do so?
Desmond had Carrie Alexander, the public spokesman of Oracle, kidnapped in order to force the mystery man to surface. The twins were surprised to find out the "mystery man" was Namor, reputed deceased for a while. Phoebe's plan had worked a bit too well, Desmond became obsessed with defeating this powerful foe. He even forced her to seduce the guy and was physically abusive when she argued. Phoebe took out her anger on her employees.
Phoebe soon found herself sharing Namor's romantic interest with Carrie Alexander. To her surprise, she was actually falling in love with him. She helped turning Desmond's attention against Stark for a while. But her twin brother was increasingly becoming both obsessive and physically abusive. He was determined to always be "in charge". Namor meanwhile had started buying out Marrs stock holdings.
When Namor, Carrie and Namorita left for a mission to the Savage Land, Phoebe followed them there. Meanwhile Desmond was left caring both Marrs Corporation and Oracle, following a personal request by Namor. Phoebe found an unwanted admirer in Ward Meachum, Namor's current opponent. They returned to New York City to find Desmond dead. He had tried to expand his operations to drug smuggling, attracting the attention of the Punisher. Desmond was forced to commit suicide to escape potential torture at the hands of Castle. Phoebe went to see her brother's body at the morgue, laughing and dancing around it. She considered herself free at last.
Phoebe found herself interrogated by the Punisher next but survived it. Apparently she figured she was no drug smuggler. But she was horrified to find out the financial state of Marrs. The rivalry with Namor and Stark, as well at Desmond's expenses in plots against the two men, had almost bankrupt the company. Namor promised her help. But at the time, he wasn't actually running Oracle, distracted by other matters. At the time the de facto head of Oracle was Jacqueline Crichton (Spitfire). Her help was to buy out Marrs Corp. as a wholly-owned subsidiary.
When Namor went missing, amnesiac again, Spitfire offered the position of CEO to Namorita. Phoebe was angered at being only a high-ranking executive instead of CEO. Namorita let her know that she was an employee and she was expected to behave. Namor did return but continued to neglect both his business affairs and Phoebe. Meanwhile she was orchestrating a takeover of Oracle from the inside. Namor had to comply, though remaining a major stock owner.
Both Phoebe and Namor were soon surprised to find out about some executive decisions and other machinations, supposedly by Phoebe. Only she had not authorized any of them. Llyra had been impersonating Phoebe for months in order to infiltrate Oracle. Finding her secret identity was the new CEO was a bonus. (Apparently Oracle employees were late to realize that two Phoebes were concurrently giving commands from different locations). Phoebe investigated and found out what her doppelganger was orchestrating. She alerted Namor but has not been seen since.