In addition to defending his rebellious teenage niece Julie Olson on shoplifting charges and representing Woodstock industries, Mickey agreed to handle the divorce of David and Susan Martin. This fueled the ongoing sibling rivalry between Mickey and his brother Bill, who had developed a friendship with Susan. Bill also began dating Dr. Laura Spencer, a woman in whom Mickey had become interested.
After Susan's baby Dickie accidentally died, Susan was arrested for murder and Mickey represented her. After an arduous trial that endured all summer, Susan was found not guilty.
Laura began to date Mickey when she mistakenly believed Bill was no longer interested in her. Laura and Mickey became engaged and were married just after Christmas in 1967. They honeymooned in Jamaica.
Bill was obsessed with Laura and as he saw her each day at the hospital where they both worked, his obsession grew. One night, in a drunken rage, Bill raped Laura. The next day, he asked her forgiveness. Deeply humiliated and hurt, and believing that admitting the truth of what had happened would result in violence between Mickey and Bill, Laura vowed to put the incident out of her mind as best she could.
Bill accidentally discovered the truth soon thereafter. He had mistakenly picked up Mickey's medical records instead of his own. Bill debated whether to fight for his child and Laura or to maintain his silence. He realized that confronting Mickey with the truth would do more harm than good, so he decided to remain silent.
In her eight month of pregnancy, Laura was in a car accident and had to have an emergency C-section. Michael William Horton was small but completely healthy.
As time passed, Mickey wrongly suspected Bill and Laura of having an affair. Mickey and Laura's marital troubles escalated to the point that she rejected him sexually. Mickey moved out and began having an affair with his secretary, Linda Patterson. By December of 1970 the affair was over and Mickey and Laura had reconciled. Still, Mickey found it difficult to fight his attraction for Linda. When Linda learned she was pregnant, she honestly believed that Mickey was the father.
Mickey was devastated when he learned that Linda's baby daughter Melissa was not his child after all, but the child of her ex-boyfriend Jim Phillips. Jim and Linda reconciled and moved to Boston with their child.
Laura was hurt by Mickey's affair with Linda but at first she agreed to do whatever it took to repair the marriage for the sake of her son. Laura's emotional estrangement from Mickey continued to escalate, however. She decided she would ask Mickey for a divorce so that she and Bill could be together. Mike overheard his mother and uncle professing their love for one another and ran out of the house blindly, right into traffic. While recovering in the hospital, Mike told Bill to stay away from him and his mother. At the same time, Mickey was diagnosed with a heart condition. Laura realized that Mike and Mickey needed her and she couldn't bring herself to ask for a divorce.
For a time, their marriage remained tranquil, until Mike learned about Mickey's affair with Linda. He confronted Mickey in such a rage that Mickey had a massive coronary. Laura performed CPR while Mike called 911. At the hospital, Mickey flatlined but Bill performed a life-saving triple bypass. During his lengthy hospital stay, Mickey suffered a stroke that took his memory. Disoriented, he found his clothes, dressed, and left the hospital. He disappeared from Salem without a trace.
After weeks of wandering, Mickey wandered into the farmhouse of Maggie Simmons, who had been crippled in an accident that had killed her parents, Elmer and Dorothy. Based on the initials on his belt buckle, Mickey began calling himself Marty Hansen. He and Maggie grew close. The following year, when he proposed, Maggie accepted with tears of joy.
After the wedding Maggie travelled to University Hospital in Salem, where recent advances had been made in treating the sort of injury that had left Maggie without the use of her legs. She was unnerved when she heard that Dr. Laura Spencer's husband Mickey had disappeared from Salem about the same time that Marty had shown up at the farm. She left the hospital without making a follow-up appointment.
Eventually the Hortons were led to the Brookville farm where Maggie and Mickey lived by a newspaper article about Mickey, who, as Marty, had won a farming award. They were overjoyed to find Mickey alive, but he showed no signs of recognizing any of them. He readily gave Laura a divorce, and by the end of the year, Laura and Bill had married, and Mickey remained on the farm with Maggie.
Bill performed surgery on Maggie, but when it was unsuccessful, the old animosity between Mickey and Bill resurfaced and Mickey angrily blamed Bill's ineptitude for the failed surgery. As Maggie recovered, Mickey doted on her every moment of the day and night.
Mike was injured in an accident on the farm and needed massive blood transfusions. It was then that the truth of his paternity finally came out. Outraged by the years of lies and betrayal, Mickey bought a gun and intended to shoot Bill. Tom intervened however and Mickey was committed to Bayview Sanitarium.
During the time Mickey was in the sanitarium, Maggie regained the use of her legs, and when he was released, they adopted a little girl, Janice. Joanne Barnes, Janice's biological mother, came to town and kidnapped Janice. The FBI caught up with her and Janice was returned to Mickey and Maggie, but Joanne stayed in Salem, trying to get close to the child. The stress made Maggie turn to drinking. She started a kitchen fire while drunk and then had a car accident, in which Janice was hurt, but not seriously. Joanne used Maggie's drinking and Mickey's mental breakdown to pursue custody of Janice. When she won, Maggie sunk into a deep depression.
By 1981 Mickey and Maggie had repaired their marriage. Maggie wanted to participate in Dr. Neil Curtis' surrogate mother program. In spite of initial reluctance, Mickey eventually agreed. When Maggie delivered a baby girl, she decided she wanted to keep her, and Mickey helped her to win custody of baby Sarah. They also got custody of Melissa, Linda's daughter.
In 1982, when Mickey learned about some of Stefano Dimera's criminal activities, Stefano captured him and held him prisoner on one of his islands. All of Salem believed Mickey had been killed in a plane wreck. While they mourned him, Stefano tormented Mickey with pictures of his memorial service back in Salem. After many unsuccessful attempts to escape, Mickey finally managed to get away from his island prison. When he arrived back in Salem, he found that Maggie had fallen in love with his best friend and law partner, Don Craig. Mickey suffered a heart attack, but recovered. Maggie went through with divorcing Mickey, but ultimately she stopped seeing Don and she and Mickey remarried in 1985.
Mickey had become a workaholic by 1990 and a lonely Maggie turned to Neil Curtis for comfort. Neil and Maggie learned that Neil was in fact Sarah's biological father. Sarah had difficulty accepting this and she moved to Nashville with her sister Melissa. Mickey and Maggie's marriage survived the affair.
Nowadays, Mickey and Maggie spend more time at Alice's house than they do at their traditional 3-bedroom home near the lake at 415 Ardmour. He and Maggie are Alice's main emotional support since Tom's death. They have settled into a loving and contented life in their later years.