Phoebe Marrs grew up with her twin, Desmond, in the shadow of their father, Archimedes Marrs. Archimedes headed Marrs Corp., a struggling corporation. Phoebe longed for a simple, quiet life and at age 19, she ran away to the midwest and met Michael Payne. They fell in love and married where Phoebe spent the next 18 months as a happy housewife. When Michael's business collapsed, he began to struggle with feeling useless. Desmond showed up and offered Michael a million dollars to divorce Phoebe, which he accepeted. Phoebe later realized that Desmond's hand had been in Michael's business failings as well. Three months later, Phoebe found out she was pregnant and took a world cruise after Desmond ordered Phoebe to have an abortion. After Edward was born in Singapore, she had him secretly brought back to the states and found a house in Connecticut where new employees Sumner and Miss Wickham could raise him in secret. She keept her son a secret from Desmond and the media.
After their father died, the Marrs twins struggled to balance their inheritance. They sought out the financial aid of Headhunter, a business woman who required her clients to sign a contract that would allow her to collect their 'head' years later. Desmond and Phoebe signed away, never thinking Headhunter would actually collect.
Under the leadership of the Marrs twins, the Marrs Corporation became very sucessful. The Marrs Corporation were at odds with Tony Stark of Stark Enterprises as they fought over corporate holdings. Stark beat the Marrs in buying out a company called Centrex, causing Desmond to retain a hatred for Stark.
Seeking revenge on Tony Stark, Kearson Dewitt approached Desmond and Phoebe with a plan to take Stark down. Dewitt designed a chip that would be implanted in Stark's spine that would allow the paralyzed Stark to walk again but that would, in time, give Dewitt direct control over Stark's nervous system. The Marrs twins agreed to fund the project.
One evening, Phoebe returned from a business trip in Hong Kong and grew angry with employees. She went to Desmond's apartment and Bevis, the butler, directed Phoebe to Desmond's location in the gun room. She found Desmond ready to shoot himself, and deflected the gun just in time. She renewed Desmond's interest in life by turning him on to the challenge of ferreting out the mystery man behind the new Oracle, Incorporated. Finding out the identity of this mysterious benifactor became Desmond's sole reason for living. Desmond hired Griffin to attack the Carrie Alexander, Oracle's proxy buyer in an attempt to identify the true owner. Namor was exposed as the mysterious benifactor.
Desmond consturcted a plan to destroy Namor. As part of Desmond's plan, he wanted Phoebe to seduce Namor. When she expressed concern that Namor may be too mighty a foe for them, Desmond slapped Phoebe to silence her. In an attempt to get the two to meet, Desmond pushed Phoebe off the roof, leaving Namor to catch her. After Namor did so, Phoebe kissed him in gratitude. Namor returned Phoebe to her home and she slipped into a bathrobe. Phoebe charmed Namor briefly, then received notice of Sluj, an ecological disaster, attacking a Marrs ship, the Sea Queen. When Desmond learned that Namor had gone off to investigate the Sea Queen, he was furious. He grabbed Phoebe as if to hurt her, and was shocked when Headhunter came in stating that it was time to collect.
After Namor defeated Sluj, Phoebe rushed to him, asking for help against Headhunter. In the back of her limo, she confided in Namor, then kissed him. Phoebe and Namor confronted Headhunter, demanding Desmond's return, and Phoebe wondered if another arrangement could be made (offering Namor as a trade for Desmond), but Headhunter informed them it was too late as Desmond was already mounted on her wall. Later, after Namor had defeated Headhunter and Desmond had been freed, Phoebe watched the news about Headhunter's defeat. Namor went to Marrs Corp. to confront Phoebe on her betrayal, and Desmond acted shocked and appalled at Phoebe's behavior in front of Namor. Namor left thinking Phoebe cold and ruthless and Desmond full of honor. Phoebe grew frustrated with Desmond's laughing over Namor's folly. She began to realize that perhaps she really did love Namor.
Desmond and Phoebe went to check on Dewitt in the Stark project. When they arrived, Dewitt was noting how Stark seemed to be exerting a high amount of physical activity (as Iron Man, though they did not know this). Desmond, hoping Stark would be injured, demanded that they take control of Stark's nervous system at that moment. After Desmond learned that Stark was successfully being controlled, he reasserted his power over Dewitt, reminding him who was in charge (at one time bending Phoebe's wrist to get her to stand away). After Phoebe reminded Desmond what a worthy opponent Stark was, Desmond agreed to let Kearson continue running the project and departed. Kearson tried to flirt with Phoebe, but she denied his advance and left. Stark pieced together the Marrs' involvement with the plot against him and defeated Dewitt.
Stark Enterprises launched a corporate attack on Marrs Corps in retaliation.
Her fury was replaced by pleasure when she saw that Namor had come as she'd asked. Phoebe fired Allison for muttering something, and grew defensive when Namor asked her about the firing. Softening, she convinced Namor to fly with her to Connecticut. When Sumner greeted Phoebe as Mrs. Payne, Namor was confused, but Phoebe was pleased to hear that Edward had been demonstrating conscious action in his play. Edward, of course, did not recognize Phoebe when she greeted him. Phoebe took Namor and Edward into the backyard and sadly explained her origins to Namor. The Griffin attacked them, and Phoebe watched Namor battle and tame the creature. She told Namor that he had tamed her as well, and that she was in love with him, before giving him a kiss. Namor next approached Desmond and asked him to watch over Oracle, Inc. while Namor was on an extended leave in Atlantis. Phoebe told Namor she was coming with him, but Namor declined, stated that this was a personal trip. Phoebe asked what could be too personal since they loved each other. After Namor left, Phoebe confessed to Desmond that she really loved Namor and that she wouldn't allow Desmond to harm Namor. Desmond struck her in a rage, revealing that he knew about their trip to Connecticut.
Phoebe arranged transport to the sky over Atlantis, determined to follow Namor there. She flew to Antarctica, where she found Namorita and Carrie Alexander waiting for Namor, who was investigating a mystery in the Savage Land. After Namor, Namorita, and Carrie were caged by the Super-Skrull (disguised as Iron Fist), Phoebe was taken into a shelter by the Skrull's ally, Ward Meachum. Meachum considered he and Phoebe equals and desired her company as he made a bid for global power. When Phoebe denied him, he moved to strike her but stopped himself. As Meachum again prepared to strike Phoebe, Misty Knight stopped him, and Meachum revealed their plans for the world to be destroyed. 'Iron Fist' entered and revealed himself as the Super-Skrull. The Super-Skrull foiled Misty's attempt to stop him. After the Skrull left, Ward explain his alliance to the Skrull, how they would destroy the planet, and how Ward would get his own planet to rule and the most beautiful woman in the galaxy as his reward. Phoebe ridiculed the man, pointing out to him that a Skrull's idea of a beautiful woman may not be Ward's ideal. This seed planted, Ward turned on the Super-Skrull, who was soon defeated with the help of Shanna the She-Devil and the Griffin.
Back on the ship, Phoebe was surprised to learn that Desmond had attacked and beaten Caleb Alexander, and claimed that it must have been self-defense, making Carrie very angry. Namor and Namorita returned to Atlantis, and Phoebe returned to New York.
Returning to New York, Phoebe found out that Desmond had committed suicide when the Punisher had threatened to kill Desmond for his crimes. She went to the morgue to see the body, where she laughed and danced around the corpse, utterly relieved to finally be free from the Desmond's influence.
Phoebe took time to reassess Marrs Corp standings, and realized that her business was almost bankrupt due to Stark's influence and Desmond's mistakes. She went to Namor, who consoled her on Desmond's death, and begged for his help. He agreed, saying that begging wasn't necessary. Namor appointed Jacqueline Crichton (the former Spitfire) to head Oracle in his absence. When Jacqueline determined to have the rest of Marrs Corp. absorbed into Oracle's holdings, Phoebe argued that that isn't what Namor had promised her. Furious, she tried to attack Jacqueline, but was stymied. Jacqueline sent her away. Phoebe muttered to herself that she needed Desmond to run Marrs Corp. and was shocked when a door opened and she thought she saw his form. She rushed into the next room to find it empty. (The 'ghost' of Desmond was secretly Llyra).
After six months, during which an amnesiac Namor had gone missing, Oracle was turned over to Namorita. Phoebe continually confronted Namorita on the state of Marrs Corps as a wholly-owned subsidiary, but Namorita refused to refute Jacqueline's decision and let Phoebe know she was now an Oracle employee. As Phoebe rode the elevator, she reflected on her future without Desmond when the elevator opened and Desmond appeared, wondering how Phoebe could let them stomp on the Marrs name like she had.
When Phoebe saw an opening in Oracle's business structure, she jumped on it and bought out the Oracle building, becoming its sole owner. Phoebe approached Namor and ordered he and his allies off her property. Durring this time, Phoebe had developed a reputation as being slightly crazed due to seeing her brother's ghost.
Phoebe went to Oracle for a surprise meeting of the board of directors, angry at Namor for calling it unexpectedly. Desmond instructed Phoebe to ensure that Namor stayed at Oracle overnight. Phoebe spent time contacting Oracle's employees and major shareholders to get them on her side in her bid to control the company. They argued that her stock certificates weren't valid and she revealed the loyalties Oracle had to her. Namor said he needed time to think things over.
At the next meeting's board meeting, Namor agreed to let Phoebe handle the company matters as long as she did not harm the environment. Phoebe revealed that Oracle's west coast head (Leonard Mackenzie) had embezzled funds from Oracle, Inc. in order to fund a mission to retrieve a sunken wreckage in the Antarctic. She asked Namor to investigate, though he said it would have to wait because he had a date. Later, while working with Hammond, Namor burst in and demanded to see Desmond's ghost. Phoebe led him to the office where, when confronted, 'Desmond' turned into Phoebe, shocking her. Hammond was surprised as well, realizing that he hadn't been romantically involved with the real Phoebe. Namor tossed 'Phoebe' across the room, and she revealed herself to be Llyra. Soon the Fantastic Four (Human Torch, Invisible Woman, Lyja, Thing) arrived and battled Llyra.
Phoebe recovered information about Leon Mackenzie's mission to the South Pole using Oracle's embezzled funds, and sent a team to investigate. When Namor returned to Oracle, Phoebe met Andromeda, thanked Namor for clearing up the ghost mystery, and gave him them new information.
When Namor returned from the Endurance mystery with the Antarctic vibranium, Namor accused Phoebe of being involved before realizing it must have been Llyra again. Phoebe arranged a buyer in Jack Gamelin of Roxxon for the vibranium mound, knowing that Namor would soon discover that Roxxon was now involved in Hydropolis's (Namor's new underwater city) construction. Phoebe Marrs visited Leon in jail, demanding to know why he had implicated her in his plots. Before he was returned to his cell (due to Phoebe growing agitated), she realized that his last name was Mackenzie, and that he must be a relative of Namor's. She rushed off to research this, then moved to give Namor the news. Namor later located Phoebe and the pair flew off. Phoebe shared with Namor her proof that Leon was Namor's relative, a grandson of Namor's father, and how Llyra used that relation to help Llyron gain the throne of Atlantis. Namor took Phoebe to Hydro-base, where they donned uniforms and were lowered to Hydropolis. Phoebe was impressed with the city, but was disgusted to see Carrie Alexander there. Phoebe watched as Lt. Langstrom, Roberts, and Captain America tried to arrest Namor. After a brief battle, Namor escaped.
It is unknown where Phoebe is now or her status with Oracle Inc.