Quinn Fuller was a jewelry designer who ran her own company, Quinn Artisan Jewelers, along with her son, Wyatt Fuller. Quinn worried when Hope Logan, a girl Wyatt was interested in, noticed that Liam Spencer, her on-again-off-again boyfriend/fiancé/husband, wore a sword necklace just like Wyatt's, as did Liam's father, Bill Spencer, Jr. Quinn balked at Hope's theory that Bill could be Wyatt's father, insisting that she'd only ever made one sword necklace, which she'd kept in a safe until Wyatt wanted to wear it. Hope and Wyatt tricked Quinn into running into Bill, and Quinn was forced to admit to a long-ago affair, during which Bill had given Quinn money for an abortion. Wyatt was furious that Quinn had lied about his father being dead.
Quinn was stunned when Wyatt claimed Bill's company, Spencer Publications, as his birthright, and declared he was also going after Hope. After Wyatt ran afoul of Bill, Quinn and Wyatt reconciled, and Quinn was thrilled that Hope wanted Quinn to design jewelry for her high-profile fashion collection at design house Forrester Creations. Quinn was charmed by Forrester's CEO, Eric Forrester, then overheard Hope arguing with Liam, who wanted Hope to kill the deal because he didn't want her working so closely with the amorous Wyatt. Quinn made a beeline for Eric's house and was wowed by the luxurious surroundings; stealthy Quinn listened as Eric told Hope the deal would be honored and surprised Eric with a thank-you kiss.
With Hope and Liam's wedding approaching, Quinn sent Wyatt and Hope to Mexico to retrieve a special diamond for Hope's clothing line, Hope for the Future. Learning that Liam had made a tribute video as a way of saying goodbye to his ex-wife, Steffy Forrester, Quinn broke into his e-mail and forwarded it to Hope, which ended Hope's engagement to Liam and pushed her closer to Wyatt. Liam discovered Quinn's treachery and Wyatt's after-the-fact complicity, but the damage had been done. Quinn heard Bill telling Wyatt to back off of Hope out of respect for Liam, so she stuck Bill with his sword necklace, licking the blood and saying revenge tasted sweet. Quinn was ecstatic when Eric invited her to the big Forrester Thanksgiving dinner and told her to consider herself part of the family. Quinn spied Eric's ex-wife, Donna Logan, giving Eric a kiss, so she confronted Donna and called her a slut.
Knowing that Steffy continued to be a source of conflict between Liam and Hope, Quinn took advantage when Steffy visited from Paris, hopping a plane back to Europe with her. Quinn got Steffy to admit that she had abandoned Liam because an accident had left her barren; when a doctor called to tell Steffy that the procedure she had secretly undergone made it possible for her to have children, Quinn pushed Steffy to tell Liam, who was set to marry Hope. Steffy's presence on Liam and Hope's wedding day stopped their ceremony, and Hope moved on to Wyatt, just as Quinn planned.
Quinn sprang into action when security footage surfaced of Wyatt pocketing the HFTF diamond and planting it on arriving jewel thieves. Since the Forresters, and the world, believed that Wyatt was a hero for stopping the thieves, Quinn threatened the diamond's guard, Charlie, into keeping his mouth shut; Quinn also befriended Charlie's girlfriend, Pam Douglas, in an effort to muzzle him. But Pam caught on and showed the footage to Liam, who wanted to prove that Wyatt and Quinn were not who they claimed to be. Quinn trapped Liam in a freight elevator to keep him from exposing Wyatt, which Liam did as soon as he escaped.
Quinn was relieved when Hope forgave Wyatt and kept his “theft” to herself, but Quinn still wanted Liam gone; she noticed that young Aly Forrester had a crush on him, so Quinn gave Aly a makeover and sicced her on Liam. But Aly, who had mental issues from traumatically losing her mother at a young age, became a problem for Quinn when she directed her rage at Wyatt: Aly discovered that Wyatt had “stolen” the HFTF diamond to make himself look good to Hope and wanted to go to the police. Quinn grabbed the girl and held her over a second-story railing to terrorize her into keeping quiet. Although Aly fought back and ran straight to Eric, Quinn scored another victory when the Forresters decided to bury Wyatt's involvement with the diamond theft to prevent a media scandal.
Quinn found she was still intrigued by Bill, who had just been dumped by Hope's mother, Brooke Logan. Quinn and Bill's bickering soon progressed into a night of raucous S&M sex. Bill swore it wouldn't happen again, but Quinn snuck into Bill's bedroom, and their rough passion exploded once more. When Brooke came over wanting to talk, Bill stashed Quinn in his closet. Quinn had taken a selfie of herself next to a naked, sleeping Bill, and later used it to manipulate Bill into officially making Wyatt a Spencer. Then, Quinn trapped Liam in the Forrester steam room and cranked up the heat in an attempt to keep him away from Hope, who had decided to date both Wyatt and Liam. But when Quinn decided she wanted Bill for herself, she showed Brooke's ex-husband, Ridge Forrester, the naughty photo of her and Bill, knowing Ridge would fly to Abu Dhabi to stop Bill and Brooke's Middle Eastern wedding.
When Ridge went missing after falling out of a helicopter and into the Persian Gulf, Quinn found herself blamed by everyone at Forrester Creations. Wyatt punched Liam for calling Quinn a “vile, manipulative, evil bitch,” but the violent act convinced Hope to choose Liam over Wyatt, even after Quinn stole the keys to the Forrester cabin in Big Bear so Wyatt could propose to Hope. Forrester terminated its contract with Quinn Artisan Jewelers, and Wyatt wanted nothing more to do with Quinn. Drowning her sorrows at a bar, Quinn met Deacon Sharpe, the man who just happened to be Hope's estranged father. Quinn offered Deacon a place to stay if he would help push Hope back toward Wyatt.
Holding Liam responsible for all her problems, Quinn stabbed Liam in the throat with his sword necklace during an argument, then told Deacon she wanted to kill Liam. Deacon thought Quinn was joking, but Quinn went to work welding a mysterious contraption in her warehouse. On a windy night, Liam was startled when he investigated banging noises around his house and saw Quinn's face outside his patio door. Quinn told Liam she would kill him and Hope if he didn't stay away from her, then showed Deacon a full-size version of the Spencer sword necklace she had made. Quinn returned to Liam's house under the cover of noisy Fourth of July fireworks and was ready to impale him with the sword when Wyatt walked in and stopped her. Neither Wyatt nor Liam wanted to call the cops, so Quinn ran away.
Before long, Quinn sent Wyatt a text, reporting that she had checked herself into a psychiatric hospital. A few weeks later, Quinn came home to a dispassionate Wyatt, who had inherited the HFTF diamond from its owner, Ricardo Montemayor. Quinn encouraged Wyatt to give the diamond to Hope to win her back from Liam. When Quinn learned that Liam was set to meet Hope in Paris to get married, she followed Liam overseas and pushed his new friend, Ivy Forrester, into the River Seine, knowing he'd jump in to rescue her. Quinn watched via stolen binoculars as the delay caused Liam to be late, and as Hope got fed up and left with Wyatt. Quinn called Wyatt and told him to take advantage of his opportunity, and was later thrilled to learn that Wyatt and Hope had gotten married on Bill's yacht in Monte Carlo.
Quinn came home to find that Deacon had discovered a video Ricardo had made for Wyatt, which made several oblique references to Quinn; Deacon had been told by a detective that Ricardo was murdered, and when Deacon accused Quinn, she pointed a gun at him. Quinn claimed she was innocent of any wrongdoing regarding Ricardo, then told Deacon that she knew he wanted Brooke back and could help him win her. Quinn admitted she wanted Bill for herself and didn't want to see him reunite with Brooke, so she hatched a plot to keep them apart: she would get Ridge to do the dirty work for her. Quinn approached Ridge under the guise of making amends for her part in Bill dumping him out of the helicopter, then lifted discarded designs out of his wastebasket; the unintelligible scribbling told Quinn that Bill had caused Ridge to lose his designing ability. Quinn attended Wyatt's homecoming party, where she sent Deacon to tell Brooke the truth about Ridge. Quinn was happy when Brooke once again put distance between herself and Bill.