Kissed Hope Logan knowing she was engaged to Liam Spencer 
Stole the Hope for the Future Diamond, then planted it on actual jewel thieves to impress Hope 
Punched Liam Spencer 
Wyatt Fuller was taking a solar shower at his campground in Big Bear, California, when he heard a click behind him: it was a young woman snapping a photo of Wyatt in the altogether. The girl ran but hit her head; as she came to, Wyatt impulsively kissed her and learned that she was Hope Logan of Forrester Creations. Hope lamented the absence of Liam Spencer, her on-again-off-again boyfriend/fiancĂ©/husband, who was working through being deserted by his wife, Steffy Forrester. Wyatt scoffed at Liam's inattention to Hope and expressed his own interest in her, introducing her to his mother, jewelry designer Quinn Fuller. After noticing that Wyatt's sword necklace was identical to the ones worn by Liam and his father, Bill Spencer, Jr., Hope arranged for Bill and Quinn to run into each other, and it came out that Wyatt was also Bill's son from a long-ago affair with Quinn. Wyatt, who had been told his father was dead, was furious, but eventually forgave his mother.
Wyatt moved in with Liam and Hope, wowed by the trappings that came with being a Spencer. After overhearing Liam and Hope arguing about not being able to marry for six months because Steffy wanted a divorce and not an annulment, Wyatt told Hope she'd never be second best with him. Liam punched Wyatt after catching him kissing Hope. Wyatt increasingly felt that a place at Spencer Publications was his birthright.; also wanting Hope, Wyatt told himself that Liam was the only thing keeping him from both. But Wyatt alienated Bill when he found out that his baby half-brother, Will, would also grow up without a father because of his affair with his wife's sister, Brooke Logan, and Bill threw Wyatt out of the family. Brooke helped Wyatt reconcile with Bill, and, by extension, Quinn.
Wyatt was thrilled when Hope wanted Quinn's company, Quinn Artisan Jewelers, to partner with Forrester Creations to design accessories for its Hope For the Future (HFTF) line. But when Steffy gave Liam his annulment, leaving him free to marry Hope, Quinn worried that Hope would pull out of the partnership, so she sent Wyatt and Hope to Mexico to procure a special diamond for the collection. Wyatt insisted that Hope had feelings for him, and suggested she marry him instead of Liam. Hope called off her engagement to Liam when she anonymously received a tribute video he had made for Steffy; Wyatt learned that Quinn had broken into Liam's e-mail and forwarded the video to Hope. Liam learned of Quinn's deception, but Hope didn't hold Wyatt responsible. Buoyed by Hope's generosity of spirit, Wyatt stepped up his pursuit by pocketing the HFTF diamond so he could impress Hope by "rescuing" it; however, he didn't count on being held up by actual jewel thieves. Wyatt planted the diamond on them and was branded a hero by the Forresters and the media.
Hope remained determined to marry Liam anyway, but ditched him when she saw him talking to Steffy, who was visiting to tell Liam she was no longer barren, which is what drove them apart. Wyatt accompanied Hope to Hawaii, but Liam followed, having discovered that Quinn had brought Steffy to town to ruin the wedding. Though Hope understood, she sent Liam on his way, deciding to date Wyatt. When Bill gave Wyatt his old beach house, Wyatt wanted Hope to move in, but Hope insisted she wasn't ready. Instead, Wyatt whisked Hope away in a vintage trailer, where they made love for the first time on a beach. Liam confronted them with security footage of Wyatt snatching the diamond; Wyatt was relieved when Hope forgave him and convinced her brother, Forrester president Rick Forrester, to keep Wyatt's "theft" under wraps to avoid a media scandal.
Wyatt had an idea that would tie the jewelry collection of departed Forrester matriarch Stephanie Forrester to an upcoming HFTF showing, and traveled to Paris with Hope to present the idea to the Forrester International office. Everyone, including Stephanie's son, Thorne Forrester, who ran International, loved the idea -- but Thorne's daughter, Aly Forrester, stamped her feet that Wyatt was distracting Hope from HFTF's original purity message. Aly, who had mental issues over traumatically losing her mother, Darla Einstein, at a very young age, slapped Wyatt when he bragged about having had sex with Hope on the plane, and freaked when she walked in on Wyatt and Hope in bed together. Aly learned how Wyatt had "stolen" the HFTF diamond and went straight to Forrester's CEO: her grandfather, Eric. Wyatt offered to turn himself in to the police, but Eric chose not to go public with Wyatt's misdeeds.
Wyatt was disappointed when Hope had a pregnancy scare but turned out not to be pregnant, and even more so when Liam convinced Hope to date both him and Wyatt. Bill surprised Wyatt by officially making him a Spencer, although Wyatt didn't know that Quinn had forced Bill's hand by threatening to go to Brooke's ex-husband, Ridge Forrester, with a photo of Quinn and Bill in bed if Bill didn't comply. When Quinn told Wyatt she intended to use the photo to break up Brooke and Bill, Wyatt begged her to consider how her actions would impact his relationship with Hope, but Quinn showed Ridge the selfie anyway; Ridge stopped Bill's wedding, but fell from a helicopter and went missing. Wyatt punched Liam for calling Quinn a "vile, manipulative, evil bitch," but Hope saw the fisticuffs and chose Liam, even after Wyatt proposed.
Forrester Creations terminated their contract with Quinn Artisan Jewelers; having lost Hope and his job because of Quinn, Wyatt told his mother he wanted nothing more to do with her. Wyatt was horrified to learn that Quinn had stabbed Liam in the throat with his sword necklace during an argument, and surprised when Hope's estranged father, Deacon Sharpe, paid him a visit. Wyatt bonded with Deacon as they discussed Hope, not knowing that Quinn had involved Deacon in her latest scheme to win Hope for Wyatt.
When Liam came to Wyatt with news that Quinn had threatened to kill both him and Hope, Wyatt begged Liam to hold off on calling the police until he had a chance to talk to his mother himself. Looking for her at Quinn Artisan, Deacon reported that Quinn had admitted a desire to kill Liam, and that she had made a giant sword. Wyatt ran to Liam's and got there just in time to stop her from impaling Liam through the heart. Neither Liam nor Wyatt wanted to involve the cops, so Quinn slipped away. Wyatt and Liam bonded over the ordeal, and, soon after, Wyatt received a text that Quinn had checked herself into a psychiatric hospital.
Wyatt agreed to be the best man in Liam's upcoming wedding to Hope, but had second thoughts when he inherited the HFTF diamond from its owner, Ricardo Montemayor. As he had once promised Hope the diamond, Wyatt presented it to her and pressured her to accept it privately, then publicly at a press conference he arranged. Wyatt was surprised when he received a call from a Mexico City police detective, who reported that Ricardo had been murdered; when Quinn came home from the hospital, Wyatt briefly wondered if his mother had been responsible for Ricardo's death.
Wyatt, who had been rehired by Forrester to act as a liaison for new jewlery designer Ivy Forrester, was sent to Paris with Hope for a photo shoot involving the diamond. Wyatt, knowing that Liam had walked out on Hope for accepting the diamond, scoffed when Hope said she had told Liam to meet her at a predetermined time at the Eiffel Tower for a reunion and to get married; if Liam didn't show, Hope would know he considered their relationship over. The time came, and Liam was nowhere to be seen, so Wyatt flew Hope to Bill's yacht in Monte Carlo and asked her to marry him instead. Hope said yes, and she and Wyatt enjoyed honeymooning on the boat, then came home to a party Bill had arranged for the newlyweds. When Bill forced Liam to attend and put him on the spot to congratulate his brother, Wyatt saved Liam by changing the subject. Wyatt raised an eyebrow when Aly and Ivy suddenly wanted details about the wedding, and, when Bill told Wyatt how Liam had actually been in Paris, he knew the girls were distracting him so Liam could tell Hope.
Buoyed that Hope had told Liam she would remain Wyatt's wife, Wyatt decided he wanted Liam's bigger house to raise a family, but Liam refused to hand anything else over to his half-brother. Later, Wyatt learned that the only reason Liam had flaked on Hope in Paris was because Quinn had pushed Ivy into the River Seine to distract him. Wyatt begged Hope not to go back to Liam, then received a surprise when Hope told him he was going to be a father. Wyatt shared the news with Quinn, then walked in on his mother and wife in a heated discussion over Hope's refusal to let Quinn be a part of the baby's life; Hope was horrified that Quinn had threatened her, while Quinn told Wyatt that Hope had misunderstood. Wyatt supported Hope's position, but felt torn between her and Quinn -- at least until Quinn ambushed the baby's first ultrasound decked out in hospital scrubs. Wyatt understood when Hope wanted to get a restraining order against Quinn.
Ivy's jewelry line was slated for a launch in Amsterdam with Hope and Wyatt in attendance; Wyatt was disturbed to see how unhappy Hope was about Ivy inviting Liam to join them overseas. Since Liam and Ivy were exploring a relationship, Wyatt listened when Quinn told him to help things along, which he did by arranging a romantic boat ride for Liam and his new girlfriend. When Hope found out, Wyatt was stunned to hear Hope comparing him to Quinn, telling Hope she couldn't have both Spencer brothers. On the flight home, Hope apologized for overreacting, and Wyatt was relieved when Hope agreed to concentrate on their marriage instead of Liam from now on.
Despite Wyatt continually telling his mother to back off of Hope about the baby, Quinn kept trying to win his wife over. Wyatt complied when Bill insisted the best way to handle Quinn was to file a restraining order against her; before Wyatt could serve it, he received a call that Hope was in the hospital, having fallen down a flight of stairs. Hearing that Quinn had once again confronted Hope, Wyatt was relieved when Hope assured him Quinn had nothing to do with her fall, but he was devastated to learn that they had lost their unborn son. Wyatt's jaw dropped when Hope held him responsible and told him their baby would have lived if he had kept his mother away. Inconsolable over the fact that Hope walked out on him and left on an extended trip for the Forrester office in Milan, Italy, Wyatt turned a deaf ear when Quinn appealed to him for forgiveness.
Rick, who was now in tyrannical control of Forrester, didn't take kindly to Wyatt shirking his duties by following Hope to Milan, and when Wyatt came home and talked back to Rick, Wyatt found himself out of a job. Liam, who was tired of Rick's mistreatment of Ivy and Caroline, decided to effect a hostile takeover of Forrester, so Wyatt agreed to beg Rick for his job back so he could spy for Liam. Later, Wyatt happily agreed to be his father's best man as Bill remarried Katie.
Wyatt accepted Quinn's Valentine's Day overture, but became concerned over Quinn's relationship with Deacon, since Deacon had a long history with Brooke; Wyatt was afraid Quinn would become violent again if Deacon betrayed her. It was soon revealed that Wyatt had served Hope with divorce papers -- Wyatt told Brooke, but was surprised by how much his soon-to-be-former mother-in-law was drinking. Wyatt then shared the news with Quinn, admitting that he saw himself in her when thinking back to how he had manipulated Hope into a relationship, knowing Hope's heart was with Liam all along.