Nick initially came to Salem to help out with the case of Steve and Kayla Johnson, who were poisoned while at Salem University Hospital. He quickly found himself falling for Chelsea Brady (then known as Benson), and decided to stick around Salem. Chelsea didn't seem to have any romantic interest in him, and the two became reluctant friends. Just when it seemed Chelsea was falling for him, she learned that he was using the online identity Lonely Splicer to get to know her and pushed him out of her life. Because of her rejection, Nick had a one-night-stand with Billie Reed, Chelsea's mother! Ironically, just as Chelsea was ready to forgive him, she learned that he had slept with her mother and was furious. Eventually, the two were able to get back on track, and finally made love.
Nick and Chelsea continued their relationship despite set backs - Chelsea's flirtatious friendship with Jett Carver and Nick's marriage to China Lee. While suffering the after effects of a bomb explosion, Nick unknowingly married the con woman China Lee in Vegas. Nick became the step-father two her two kids, Artemuis and Demarquette, when China Lee went to jail. Nick grew close to the kids and soon learned that they were the sons of a wealthy foreign dignitary. Nick eventually saw that the boys were returned to their father.
Nick took a job at the Salem University Hospital working with DNA testing. While there, he was blackmailed by Kate Roberts to send back false paternity reports making it appear that EJ was the father of both of Sami's twins. Nick eventually felt so guilty that he ran the real test. When the hospital found out that he had purposely corrupted the first test, he lost his job at the hospital.
Nick's relationship with Chelsea ended in the spring of 2008. She had developed feelings for Dr. Daniel Jonas and told Nick that she was ready to move on. Nick wished her well and began focusing on his new career.
Nick took a new job as an Associate Professor at Salem U and began working on a grant proposal for an alternative energy source. He worked as an apprentice role under the Dean of the physics department, Trent Robbins. While working on the grant, he caught Max Brady taking an odd interest in his work. Max ripped pages out of Nick's notebook and corrected Nick's work. When Nick finally did receive the grant, he felt that Max was due most of the credit. Nick urged Max to develop his knack for physics through college courses. But, Max refused because he did not want to risk more interaction with Dean Trent Robbins - who was Max's biological father. Determined to help Max find out more about his biological family, Nick stole Trent's cell phone and gave it to Max. Max learned that he had a biological half-sister named Melanie and went to France to find her.
When Max left for France, Nick stayed behind to smooth things over with Trent. But, Nick soon recognized Melanie's picture as a famous video blogger "Premier Party Girl." Nick left for France to tell Max where to find Melanie. But, Nick ran into Melanie first. Between her feisty attitude and his street smarts, sparks flew between Nick and Melanie. While in France, Nick learned that Melanie's father was pimping her out to pay off a gambling debt. Nick followed Melanie to a party where one of her father's associates was trying to pressure her into sex. Nick was shot in the shoulder trying to rescue Melanie. Despite being injured, Nick recovered and Melanie was saved.
Nick and Melanie returned to Salem. Nick confronted Trent and told him to stay away from Melanie. A few days later, Trent ended up dead and Melanie was one of the main suspects. Nick fiercely defended Melanie against attacks from the police and the general public. Distraught over the happenings of the past weeks, Nick drank wile intoxicated and was arrested for a DUI. Despite Maggie, Hope, and Chelsea's warnings, Nick insisted that everything was okay. Only things were getting worse.
Nick had not stopped taking the prescription pain pills from his gun shot wound and showed signs of full blown addiction. Additionally, Melanie had turned her interests towards other men. She decided that she was going to leave Salem. Suddenly she began receiving threatening notes and phone calls, fingering her for Trent's murder. Nick convinced Melanie to move in with him so that he could take care of her. But, Nick was the one sending Melanie notes and leaving the messages in order to keep Melanie close to him. Then, Nick convinced Melanie that she was the one who actually killed her father. But the truth was that Nick was the one who really killed Trent. Nick had been playing mind games with Melanie to keep her near him. He convinced Melanie to flee Salem with him and get married so they couldn't be forced to testify against each other.
Nick's plan soon unraveled. The night before they left Salem, Melanie and Nick checked into a motel room. Melanie noticed the pills and deduced that Nick was the real killer. Melanie tried to escape, but Nick would not let her. Back at Maggie's house, Bo, Hope, Maggie, Chelsea, and Max put the pieces together and learned that Nick killed Trent and kidnapped Melanie. Bo, Hope, Philip, and Stephanie arrived at the hotel just in time to save Melanie and arrest Nick.
Nick was immediately taken into custody. While in jail, Nick finished his alternative fuel project. To make amends for what he had done to Melanie, he signed over his rights for the project to her, making Melanie the sole owner of the project. Melanie sold the project to the highest bidder, Titan. Despite Philip's efforts to convince Nick otherwise, Nick remained convinced that Melanie should have control over the whole project.
Nick's sentencing came on January 14, 2009. Judge Fitzpatrick presided over the hearing. EJ represented Nick on behalf of Mickey's law firm. Maggie testified to the person that Nick was before the pills. And, Melanie asked that Nick be shown mercy. The judge agreed with Maggie and Melanie. Nick was sentenced to 2-4 years with an eligibility of parole after 18 months. After saying goodbye to Max, Stephanie, Melanie, and Chelsea, Nick was sent to a correctional facility to serve out his sentence.
In August 2012, Nick came up for parole. Apprehensive at first, Melanie eventually testified that she would not stand in Nick's way of getting parole. Nick was released, but was told that he must stay in Salem as a condition of his parole and live with a family member. He moved in with Maggie and Caroline, whom he had written to in prison, offered him a job at the Pub. Nick started his life over.
He quickly met and fell for Gabi Hernandez, who also worked at the Brady Pub. Gabi and Nick started dating, making Chad even more mad, as Nick had previously kidnapped and stalked Melanie. One night, Chad saw Nick with Melanie's scarf and assumed he'd hurt Melanie again, so Chad assaulted Nick. Gabi broke it up and took Nick to the hospital.
Gabi had confided some of her misdeeds to Nick, so in an attempt to keep Chad from harassing her further, Nick made a deal with Chad- Nick wouldn't go to the police about Chad's assault, if Chad wouldn't go to the police about Gabi's involvement in Melanie's kidnapping. Nick thought that Gabi was in the clear and looked forward to a happy future with her.
But, Nick was different this time around. He was much more guarded and unforgiving since his time in prison. When Gabi suggested double dating with Will and Sonny, Nick told Gabi that he believed that Will and Sonny were living a biblically sinful lifestyle. While he did not wish them harm, he did not want to associate with them. Gabi did not object.
One day, when Gabi fainted one day at work, Nick rushed her to the hospital. Gabi found out that she was three months pregnant. Knowing that the baby couldn't be his, a furious Nick assumed that Gabi had slept with Chad. But, when Will confessed to being the father, Nick's anger turned to concern.
Nick presented Gabi with a proposal -- marry him and let everyone think that he is the father of the baby. Gabi agreed and the two of them convinced Will that this was the best move for everyone. As soon as Will agreed, Gabi and Nick went forward with their wedding plans, with Sami stepping in as their wedding planner.
But on the day of their wedding, Chad exposed Gabi's secret -- that Nick was not the father of Gabi's baby. Will, reluctantly, admitted that he was the father. Sami was furious with Gabi. Rafe was angry with Will. And Nick was worried that his plan to keep gay Will out of the baby's life was now in jeopardy. So, Nick hatched a plan.
He had overheard Lucas scream at Will, "I went to jail for you!" Nick began investigating why Lucas had been in prison. Nick also planted a transmitting and recording device on Will, then sent a text to Lucas prompting the two to have a conversation where Nick found out that Will was the one who shot E.J. in 2007 and the police still had evidence of it in their evidence room.
Nick had papers drawn up for Will to sign that would release all parental rights to Gabi's baby and just waited for the right time. That time came when Gabi started having labor pains while talking to Sami. Gabi and the baby were fine, and despite Kayla saying that dehydration contributed to her labor pains, Nick used Sami's temper as an excuse to set his plan into motion.
Nick confronted Will with the deal -- if Will signs away his paternal rights, Nick will stay quiet about Will shooting E.J. Nick also pointed out that turning in Will would mean incriminating Lucas, Roman, Hope, and more in the cover-up. Sonny, E.J., Sami, and Lucas all tried to convince Will not to sign the papers. Sami even offered to sign a document that would forbid her from coming near the baby. But Nick would not agree. Despite protests from Sami, Lucas, E.J., and Sonny, Will reluctantly signed the papers. Nick went to Gabi and asked her to marry him. The two were married two days later in the Horton living room.
Sami was determined to destroy the evidence Nick had against Will, so she enlisted some help. Sami and Sonny broke into Nick's room and stole some of his USB drives. They were trying to find the recording of Will confessing to shooting E.J. However, while searching through the drives with E.J. and Will, E.J. found a file titled "Mad World" and copied it onto his own computer. The file contained the formula to a new anti-aging product that Mad World was launching.
Nick admitted that his real problem was that he didn't think Will should be a father because Will was gay. Nick also stated that the baby would be better off it Will and his whole family would stay away. Will was crushed.
Thinking that he was finally getting everything that he wanted, Nick set about planning his happy life with Gabi and her baby. However, Nick's former cell mate, Vargas, was released on March 15, 2013. Vargas and Nick had made a deal in prison and Vargas was ready to collect on that deal. Nick worked some scheme that turned a small amount of money into a large amount of money for Vargas in a short amount of time.
Nick never told Gabi about what happened, nor the enemies he made in prison. When Gabi was nine months pregnant, one of Nick's prison mates, Jensen, was released on a technicality. Jensen went right for Nick. But Jensen mistook Rafe for Nick and brutally beat Rafe with a pipe, leaving Rafe in a coma. Gabi was crushed. But Jensen wasn't done.
Jensen finally caught up with Nick in the Horton Town Square. Gabi was with Nick. Jensen kidnapped them both and took them to an warehouse on Smith Island where he tied them up and pulled a gun on them. Will and Sonny had witnessed the confrontation and followed the three of them to the cabin. Will and Sonny were able to rescue Gabi. Sonny left with Gabi while Will stayed behind to untie Nick.
Nick told Will to leave him, but Will kept trying to rescue Nick. When Jensen returned to the cabin, Will hid and heard Jensen confess to raping Nick in prison. When Jensen pulled a gun on Nick, Will jumped out and hit Jensen with a wrench. Jensen and Will struggled. The gun went off. Will was hurt. At that time, Hope and the police arrived. Hope fatally shot Jensen. They all took Will to the hospital. Will made it through surgery successfully. But Nick was far from recovered.
Nick knew that he had to start telling people that he was raped in prison. He told Maggie, then Gabi. When he told Gabi he also confessed that he tried to burry everything that had happened to him and use her and her baby to start a perfect life. While he did truly care about her, he wasn't honest with her about his intentions. He also said that the rape had made him homophobic, even though neither he nor Jensen was gay, and Nick was horrible to Will and Sonny. Gabi still wanted to work things out, but Nick thought than an annulment was best. Gabi reluctantly agreed.
Shortly after, Kate found out that DiMera Enterprises had a copy of the Mad World anti-aging formula. She fired Nick, citing breach of contract due to security issues. Nick accepted her decision. And, in an attempt to make amends, he gave Kate a new formula that he'd been working on while under contract with Mad World. He claimed that it would top the file that E.J. stole.
With no job, Nick went back to Vargas to ask if he wanted to go into business together. It was unclear what the business was, but it's believed that they acted as bookies for horse racing bets. When Vargas got arrested on non-related charges, their business ended. Nick continued to do some work for Mad World on a consultant basis.
As Nick's parole came to an end, he reached out to Gabi to see if their relationship could be revived. She and Nick ended up sleeping together. Nick assumed that this meant they were on their was to reconciliation. But Gabi told him that she wasn't ready for anything and just wanted to be friends.
However, Nick was sure that if Gabi was away from Salem she'd see that they belonged together. So, he applied for and accepted a job offer in New York City. Then, he began sending out her resume to modeling agencies in New York. One of them called Gabi and offered her a lucrative contract if she'd move to New York. Gabi told Nick about the contract and he encouraged her to do what was best for her and consider it a great opportunity. Gabi first decided to take the job, but then after talking to Sami and Will, she changed her mind and told Nick that she'd make a mistake and wasn't taking the job.
Nick was upset and begged Gabi to take it. He let it slip that she couldn't turn this down after how hard he'd worked to set things up for the three of them. Gabi asked him what he was talking about and he confessed to sending out her resume for her. Gabi was furious and accused Nick of playing God with her life. Nick pleaded with her to understand. They were having this conversation in the middle of the town square and people began to stare, including Kate Roberts, who overheard the whole fight. Gabi told Nick that she wanted nothing to do with him and stormed off. Nick chased after her. Kate chased after both of them.
Nick followed Gabi into the woods around town and continued to beg her for another chance. While trying to get away, Gabi tripped and fell on the ground. Nick jumped on top of her and starting kissing her. Thinking that he was going to rape her, Gabi grabbed a rock and hit Nick in the side of the head. Nick collapsed next to her and Gabi made her way out from under him. Kate arrived and saw an unconscious Nick and Gabi in tears. Sami, whom Kate had texted to meet her, arrived shortly after. Sami checked Nick for a pulse and couldn't find one. Kate noticed that the river wasn't far from the spot and suggested that they just throw Nick's body into the river. Sami agreed to help because Gabi was the mother of Will's baby.
Gabi was hysterical over the events that just happened, but agreed that this was the right thing to do. The three women dragged Nick to the river and pushed him in. Just as he hit the water, Nick woke up and grasped at them for help. But, they'd already let him go into the cold water. The three women assumed that he would drown and die. They agreed to keep all of the events of the night a secret. In the subsequent days, Gabi and Sami had visions of an injured Nick haunting their dreams.
On the day of Arianna's christening, an alive Nick Fallon showed up at the church, much to the shock of Gabi, Sami, and Kate. Nick had a scar on the side of his head from where Gabi had hit him with the rock, but otherwise didn't seem to remember the events of that night. Nick claimed that he was there to see Hope, but the Sami and Kate were suspicious.
Their suspicions were confirmed when Nick let it slip that Kate and Sami had tried to kill him. The women were furious to hear that he had been faking him memory the previous few weeks and suspicious of why he didn't blame Gabi as well. Nick insisted that the two of them had manipulated Gabi. Nick explained that he was able to hold onto a branch in the river and a man -- Percy, who was bird watching at the river at the time -- pulled him to safety.
Percy insisted that Nick call the police. But Nick told Percy that he would make it worth his while if he didn't involve the police. Percy agreed. It also turned out that Percy had pictures of the women throwing Nick's body into the river, which he sold to Nick.
Nick used the pictures to blackmail Kate into giving him a job at Mad World and hiring Percy as his assistant. Nick insisted to Gabi that he didn't go to the police because he just wanted a fresh start. Gabi believed him. But Sami and Kate didn't buy his story at all.
Slowly, Nick started to show his true colors to other people. He blackmailed E.J. and Abigail with photos of their affair. He manipulated Will and Sonny by threatening to send Sami, Kate, and Gabi to jail. He found a lawyer for Gabi and urged her to sign custody papers that would only allow Will to see Arianna every other weekend. He got into a physical altercation with Abigail's new friend, Ben, who had stepped in to protect Abigail when Nick grabbed her arm. Everyone seemed to be growing tired of Nick.
The only person who still believed in him was Julie. She had a heart-to-heart with him one night about how she used to cause trouble too, was angry with the world, but was given another chance. She urged Nick to get professional help and embrace the second chance he'd been given. Tearfully, Nick thanked her, agreed to have dinner with her later, and left a message for Marlena, asking her to set him up with some mental health care.
But as he was leaving the message, Nick was shot three times. He stumbled to the square and collapsed in Julie's arms. He died a short time later. Hope led the investigation to find his shooter. It turned out that Gabi had finally overheard Nick's threats to Sonny, retrieved a gun from the closet, and shot Nick to death. She turned herself into the police and plead guilty.