Diane Dixon was the wife of Marcus Dixon. She, like many of Sydney's friends and associates, was unaware that her husband was working for SD-6. She was killed by Allison Doren after Marcus accidentally killed Sloane's wife, Emily. She is survived by her children, Robin and Steven Dixon.
Diane was the beloved wife of Marcus, believing that her husband worked for a bank in Los Angeles. She was also associated with Sydney and her friends, participating in some of their local parties, such as their Halloween Party (Doppelgänger).
She was never wary of any of Marcus' activities, up until her husband was gravely wounded in a shootout between K-Directorate agents. Sydney told Diane that some thugs tried to rob Marcus and Sydney of the account codes for the bank and he pushed her down to avoid incoming fire. Diane was somewhat suspicious, but still believed the lie and was grateful when Marcus came out the hospital safe and sound (Mea Culpa).
After the raid on SD-6, Marcus was arrested. Somehow, she figured out what Marcus really did and she separated from him, spending time at her sister's house. She found Marcus on the porch of their house in the rain and they began to talk to each other. Marcus tried to explain that he had no idea of who Sloane was and that he was working for the enemy, but Diane didn't accept his apology and told him she didn't know who he was anymore. Diane gave Marcus an ultimatum: Either quit his job or she would leave him forever. Eventually, he choose Diane (A Free Agent).
Marcus talked to Diane again after he killed Sloane's wife and told her he was transferring to another division after all that's happened. Diane, feeling more sympathy for him, told him it wasn't his fault for what happened and that he didn't have to transfer because of Emily's death. Marcus then told her he was trasnferring because of his family, not just because of what happened.
At dinner with Vaughn, Sydney and Marcus, Diane explained to Vaughn and Sydney about the world they lived in and how it forced people to lie, but she soon began to understand what they were doing and told them she was sorry and that Marcus' transfer order was rescinded.
Diane split up from Marcus, Sydney and Vaughn in her SUV to go pick up their kids and kissed Marcus goodnight, entering her vehicle. As she drove away, it exploded and knocked over several pedestrians, killing her instantly. Marcus and other onlookers screamed in the background as they looked at the wreckage, unaware that Allison Doren just slid a detonator into her pocket and drove away (Endgame).