Diana came to Salem in 1987 and was an old friend from Mike's college days. Diana came in search of a mysterious computer disk that both Victor Kiriakis and her mother Serena were looking for. The disk contained the location of a very rare, and valuable mineral.
Diana met Roman Brady II/John Black when she rescued his daughter Carrie was drowning in the river. Carrie and Diana hit it off well, and so did Roman II/John Black and Diana. However, Diana was on a mission and pretended to date Victor Kiriakis. When Diana's mother Serena beat Kiriakis to the computer disk he vowed revenge on her.
While in Greece with Victor for his nephews wedding Roman II/John Black and Diana made love, and began to pursue a relationship. However, when Serena shot Roman II/John Black he arrested her, only to find out she was Diana's mother.
Upon returning to Salem Diana's father was killed by a sniper and she inherited the Coleville fortune. Unknown to Diana, Victor Kiriakis and her mother Serena were plotting to steal the fortune away from her. Victor tricked Diana into marrying him because her mother was in danger, but the wedding was thwarted when Roman Brady II/John Black rescued Diana. On the second attempted Serena was "kidnapped" and Diana was to hand over her fortune to the kidnappers. However, Diana's assets were frozen and Diana was taken hostage by some terrorists. Diana was eventually freed and learned from Roman Brady II/John Black her mother and Victor were scheming against her to get her fortune. Diana eventually moved into Roman II/John's house for protection.
Diana wanted revenge against Victor, who had cost her the Coleville Fortune. In an attempt to get revenge Diana stole a statue from a museum and planned to frame Victor for the theft in order to get her fortune back. The plan backfired when Roman II/John learned she stole the statuette and Victor was never brought up on the charges of theft. Diana's lies and deceit enraged Roman II/John, and he broke off their relationship.
Soon after they broke up Diana moved back in with Roman II/John after her life was put in danger by Roman II/John's investigation of the Torres family. As a result of him protecting Diana the two resumed their relationship. Roman II/John and Diana eventually lured the Torres family into a trap, but they managed to elude the police, which put Diana in even more danger.
Roman II/John and Diana went away to the Bahamas until they though the threat from the Torres family had passed. Roman II/John and Diana renewed their romance, and had become engaged, but when they returned Roman II/John was almost killed in a car bombing by the Torres Family. Afterwards Roman II/John began remembering terrible feelings and memories, but was unsure where they were coming from. After he had his sister Kimberly hypnotize his Roman II/John recalled being trained in the martial arts by a man named Orion.
Diana and Roman II/John's relationship was on edge when Roman II/John began receiving hints that Marlena was alive, a picture of her appeared in a newspaper, he smelled her perfume at one of her favorite restaurant along with strawberries and whip cream. Roman II/John was puzzled by these clues, and a mysterious ring he had received. When his believed daughter Carrie Brady was kidnapped Roman II/John believed Stefano DiMera was behind it. Roman II/John, Diana, and the rest of the Brady's were lured to a mysterious island in the Bahamas. There Roman II/John found a women who was hired to impersonate Marlena, it was all part of a trap to lure Roman II/John away from the others. Stefano put Roman II/John into a trance and ordered him to kill the Bradys. The trance was broken when Diana coaxed him out of it. Roman II/John rescued Carrie, and everyone escaped the island, including Stefano.
Roman II/John proposed to Diana Coleville but their wedding never happened. First there was the problem that Marlena's death couldn't be proven since the body was never recovered, then Caroline Brady suffered a heart attack. Finally Cal Winters, Diana's supposed first husband returned from the dead. Diana's problems began to mount. Jack Deveraux had bought up half of the Spectator to kill a story about him, and he threatened to tell Roman II/John about Cal if she didn't sell him her share of the paper. Diana rushed the wedding but Cal crashed it and told everyone he was Diana's husband. Diana eventually proved that her wedding to Cal never really happened and Cal was forced to admit he had lied. However Cal was determined to hold onto Diana and during a fight with Roman II/John, Roman II/John was shot and fell into a coma. Cal Winters took the blame for the shooting and even went to prison for it, but he was covering for the real shooter. With Kimberly's help Diana underwent hypnosis and she learned that she had shot Roman II/John and blocked it out. While Roman II/John and Cal fought outside the house Diana grabbed a gun from a drawer and shot at Cal, but hit Roman II/John instead. Torn up with guilt Diana dyed her blond hair brown and quickly left town in 1989.
Phillip Coleville was the owner of the Spectator, and father to Diana Coleville. Upon his death in 1988 Phillip left his entire fortune to his daughter Diana.
Serena Coleville was married to Phillip Coleville, and was the mother of Diana.
Serena was after a mysterious computer disk that Victor was also after. When she beat Victor to the disk he vowed revenge on her. After she got the disk she began to mine a valuable mineral that the disk gave the location to. When Roman II/John Black and Diana began to see each other she tried to kill him. Roman II/John Black survived and arrested Serena, who he later learned was Diana's mother.
After Phillip Coleville was killed Serena and Victor Kiriakis began plotting to steal the Coleville fortune from Diana. Their first attempt at getting the fortune was to trick Diana into marrying Victor, but it was thwarted when Roman Brady II/John Black rescued Diana from Victor's clutches. There second attempt was to make it seem like Serena had been kidnapped and Diana was to turn over her fortune to set her mother free. This attempt was also thwarted when Diana's assets were frozen and Diana was kidnapped by a terrorist group. Diana was rescued, and learned the horrible truth about what her mother had done to her.