In January 2007, mobster Sonny Corinthos hired Diane Miller to represent him based on her reputation as a brilliant attorney with a dry wit, acerbic observations, blunt manner, and nearly perfect courtroom record. Her top-notch trial skills worked and, with Diane's help, Sonny once again escaped the long arm of the law. As Sonny was on trial for the death of Lorenzo Alcazar, Diane advised Sonny to remarry his ex-wife Carly Jacks so that she wouldn't have to testify against him. When a woman with information that exonerated Sonny stepped forward, Diane informed Sonny he could annul his marriage to Carly, but he convinced Diane not to tell Carly.
Diane next defended Sonny's top enforcer, Jason Morgan, who was implicated in the murder. Sam, who was working against Jason at the time, and Carly hated each other. Diane happened to walk into Jason's penthouse as Sam and Carly got into a fistfight. After forcefully getting their attention, Diane informed the women that the police were on their way with a search warrant to look for evidence to tie Jason to the crime. Diane kept the cops from finding anything incriminating.
Elizabeth was added to the list of witnesses for the prosecution, and Jason worried that it might be revealed that he was the father of her youngest son Jake. Opposing council Ric Lansing also knew the truth and had a videotape showing Jason with a gun and audio of Alcazar uttering the name, "Morgan," before a gunshot and a thud.
Evidence surfaced that cast doubt as to whether Alcazar was actually dead. Diane cross-examined the county coroner and got him to admit that he had never performed an autopsy on the man presumed to be Alcazar. The new information was enough to sway the jury who acquitted Jason.
Kate Howard, editor in chief of Crimson, had a mishap with a police cruiser, having sideswiped it. Diane worked a plea bargain with the prosecutor, who had a thing for high fashion. She bribed the prosecutor with couture apparel, and Kate was given community service at the hospital. Diane's love of fashion and the finer things in life, especially shoes, was enhanced by her friendship with Kate. Her occasional legal work for Kate has been rewarded with sneak peeks at the latest fashion trends and some delectable apparel.
Diane next represented Elizabeth Spencer, who was divorcing her husband, Lucky. Lucky hired Diane's rival, Alexis Davis. As the two attorneys worked together on a settlement, they began to become friends. During the proceedings, Lucky and Elizabeth agreed to share custody of Jake and Cameron.
In January 2008, both Diane and Alexis Davis were nominated for Litigator of the Year. On their way to the ceremony, they were kicked off of a plane for bickering and arguing with the flight attendant, rented a car, got stuck in the middle of nowhere with a flat tire, and got into trouble at a dive bar.
On the way home from Philadelphia, after having missed the ceremony, their rental car broke down -- again. They broke into another dive bar for shelter. Because it was freezing and the thermostat was out of order, they had to put on their cherished designer gowns and a couple of found coats over their clothes to keep warm.
During the night, Diane said she felt she didn't deserve the award and, if she were to win, she would give it to Alexis. She explained that she'd once represented a man accused of rape. The man had been accused of raping and murdering a teenage girl because she was black. He was actually guilty, and Diane knew she could have gotten him off but hadn't been able to bring herself to have a racist murderer released. However, he had been stabbed in prison, and Diane had felt that she was partially responsible for his death. Despite her guilt, she knew that she'd done the right thing. Alexis refused to accept the award, admitting that she had killed Lorenzo Alcazar's son, Luis, because he had been responsible for the death of her sister.
That April, Jason retained Diane to represent his mother, Monica, after she was arrested for drunk driving and hit-and-run, which occurred the same night that Alexis' daughter, Sam, had been hit by a car. At the trial, Sam stated that she wanted to drop the charges, but the judge refused. Alexis and her nephew, Nikolas, argued that Monica should not be sentenced because she was a valuable asset to the community. Monica was sent to rehab and given six months of community service.
After Sonny's eldest son, Michael, was shot in an attempt on Sonny's life, Diane and Alexis had drinks at Jake's. Alexis worried about her daughters, as she knew Sonny's life endangered their safety too. Diane, having had a bit too much to drink, retreated to Sonny's house and encountered a drunken Max. He was devastated that Michael was in a coma and felt guilty that he hadn't been at the warehouse to protect Michael and Sonny. To comfort Max, Diane kissed him.
Later, Alexis walked in, shocked to find Diane and Max in the throes of passion on the couch. Sonny was furious after he found out about their relationship and ordered them to end it, even going so far as to threaten to end Max's job. After Diane failed to keep Anthony Zacchara in prison, Sonny vowed to send Max to Puerto Rico because his relationship with Diane was throwing her off her game. Max stood up to Sonny and forcefully told him to back off, which Sonny seemed to respect.
Diane tried to help Alexis devise a legal means to force Sonny to give up custody of Kristina, Sonny and Alexis' daughter.
To keep the Corinthos Empire safe from the Zaccharas, Sonny and Jason cooked up a plan to have Jason take the helm of the business, effectively allowing Sonny to retire. Once running the "Morgan Organization," Jason made it clear to Diane and Max that he had no problem with their relationship as long as it did not interfere with business.
During a break from counseling Damian Spinelli on how to woo Maxie, Diane presided over the agreement between Sonny and Carly that, to protect their boys, gave full custody of Michael and Morgan to Carly.
As Max showed Diane the engagement ring Sonny had bought Kate, Diane mistakenly believed that Max had asked for her hand in marriage. Caught off-guard, she agreed. She quickly called Alexis and admitted she wasn't ready to marry -- anyone. Max confided in Sonny that he'd jumped the gun and wanted to back out. Unbeknownst to either pair, Alexis had pushed Diane to give the ring back as Sonny advised Max to ask for it back. Once they were face-to-face, Diane and Max blurted at the same time that they were not ready for marriage.
In July, Diane agreed to help Patrick Drake sue Robin Scorpio, represented by Alexis, for visitation/custody rights of their then-unborn child. However, without any effort by either attorney, Patrick and Robin agreed during the hearing to share custody.
After Logan Hayes was found dead, Jason was arrested for murder. Diane agreed to represent him. She wanted to point the authorities toward Lulu Spencer, but Jason refused to implicate Lulu. Sonny wanted to regain control over his organization, but Jason refused, pointing to Sonny's increasingly erratic behavior. However, neither Jason nor Sonny would allow Diane to drop them as clients, so she kept representing both of them, despite the clear conflict of interest.
Upon discovering that Sonny, though engaged to Kate, had engaged in a one-night stand with his ex-wife, Carly, Diane pushed Sonny to be honest with Kate. When the truth was revealed, Kate forgave Sonny, but Carly and her husband, Jasper "Jax" Jacks, broke up. Max told Diane that it was her fault that Carly and Jax's marriage was on the rocks. Max agreed that it wasn't really cheating, since Sonny and Kate had not yet been married.
Diane asked, based on Max's definition of faithfulness, if he'd ever cheated on her. He answered indirectly, asking how he could have cheated, as they'd only had a casual relationship. Diane angrily broke up with him. Later, she broke down in Jason's arms. The following day, Max showed up with a boom box blasting Al Green's song "Let's Stay Together."
During Sonny and Kate's fall wedding ceremony, Anthony attempted to kill Sonny but hit Kate instead. Anthony framed rival gangster Andrei Karpov. Diane tried to keep Sonny's involvement with Karpov secret, but the truth was discovered. To protect Kate, Sonny broke off his engagement.
When Diane found out that Max's father, Maximus Giambetti, was headed to town, she also learned that Milo, whom their father called "Mario," was Max's half-brother. Their father had been deported to Sicily because of his mob activity. Diane, Milo, and Jason agreed to help Max pretend to be the head of the organization. As Max, Milo, and Diane showed Maximus the office, Jason arrived, dressed casually. Diane introduced him as Max's bodyguard. Over the next few days, others were inadvertently drawn into the ruse, including Carly and Claudia, who both pretended to be amorously linked to Max -- which infuriated Diane.
After Karpov was found dead, Jason was the top suspect. To help Jason, Spinelli hacked into the Department of Defense, Witness Protection, and Interpol databases. FBI Agent Rayner discovered what Spinelli had done and arrested him for treason. But Rayner was using Spinelli as a bargaining chip to get the goods on Jason or Sonny. Diane did what she could to keep Spinelli, Jason, and Sonny from being tried.
Diane agreed to represent Carly in her divorce proceedings. Naturally, Alexis represented Jax. Neither Diane nor Alexis wanted the couple to split and hatched a plan to emphasize to each of their respective clients the downside and pitfalls of divorce. The couple eventually decided to reconcile.
After the mysterious death of Brianna Hughes in the hotel room of Mayor Floyd, the Hughes family hired Diane to represent them in a wrongful death lawsuit against Patrick. Alexis begged Diane not to take the case but would not explain why it was so important to her. Alexis finally admitted to her friend that she and the mayor had once had an affair. As if things couldn't get worse, Alexis was arrested and charged with hit-and-run after someone ran Claudia off the road.
Though Alexis didn't believe she had caused the accident, she suspected that Kristina might have. Diane represented her friend, but it was Nikolas who worked his political connections to get Alexis sentenced to community service.
After Sonny discovered that Claudia was responsible for Michael having been shot and put into a coma for a year, he verbally attacked her at her birthday party. Many people witnessed his tirade. Claudia, feeling her back was against a wall, kidnapped a very pregnant Carly, stole a car, and drove away. Carly was able to get away from her captor as she went into labor and gave birth to baby Josslyn in a cabin. But Claudia found them and, in a state of mental breakdown, thought the baby was hers.
As Carly was begging for Claudia to give her baby back, Michael entered the room and saw Claudia with his baby sister in a basket. He reacted by grabbing an ax handle and striking Claudia, killing her. Jason, Sam, Carly, and Sonny helped cover up Michael's involvement.
After Sonny shot Dominic, not knowing his name was really Dante Falconeri and that Dante was his son with Kate's cousin Olivia, Diane got Sonny out on bail. The catch was, the bail was so high that he would lose everything he owned if he were to skip bail and go on the run. Despite that, Diane and Carly urged Sonny to leave town and be a free man. But Sonny refused, wanting to build a relationship with Dante. He also worried that the spotlight of Claudia's trial might turn toward Michael. In fact, Sonny decided to confess to Claudia's murder.
Diane's defense of Sonny against murder charges in Claudia's death allowed her to finally team up in the courtroom with her dear friend Alexis. The partnership took a little prodding on Diane's part, but Alexis finally saw it Diane's way and joined the defense team on Diane's terms, as a partner in Diane's firm. Once again, Diane's power of persuasion ruled the day.
After court one day, Alexis walked into her living room to find Kristina, who had been dating physically abusive Kiefer, beaten and unconscious -- just as Kiefer ran out of the house. She carried her daughter to the car and drove her to the hospital. As Kiefer emerged in the road, a stunned Alexis hit him and kept driving. Kiefer later died from his injuries. Diane informed Alexis that, because it was her second hit-and-run and the victim died, she would likely serve time. Diane advised Alexis to either confess immediately or not at all. Diane was successful in keeping Alexis from serving time, but Kiefer's father launched a civil suit.
During the contentious trial, both the Diane/Alexis team and prosecutor Claire Walsh engaged in ethically questionable tactics. Diane encouraged Maxie to perjure herself and knowingly accepted Carly's bogus testimony. The adults in Michael's life arranged for him to leave the country until the trial ended. Claire assumed that Michael's testimony would incriminate Sonny. Claire did everything she could to find Michael, including taking Morgan out of school on false pretenses to question him about Michael's whereabouts.
Judge Carroll became very impatient with their courtroom antics. As the jury deliberated, Dante connected with Michael, who had returned to Port Charles. Michael gave Dante the proof that Michael had been the one to kill Claudia -- the bloody shirt that he'd worn that night. Dante, knowing that Michael had simply defended his mother, went to court and announced that Sonny hadn't done the deed. Dante assumed that Michael would be ordered to attend counseling and given community service.
However, Judge Carroll, angry that the trial had been a farce and feeling that Michael would be better off in prison than surrounded by the violence that had dominated his childhood, sentenced Michael to five years in Pentonville with the possibility of parole after two.
Diane filed an appeal, and Claire agreed to help right the injustice. Diane helped Claire convict Jason, with the condition that Jason be sentenced to Pentonville and share a cell with Michael to protect him from the guards and other prisoners. Dante convinced Judge Carroll to reverse his decision. The judge insisted that Michael live with Dante and that he have minimal contact with Sonny. Diane began working on a way to get Jason freed but was doubtful it would work. Diane was forced to break the bad news to Jason that he wasn't getting out of prison anytime soon. However, Claire agreed to let Jason out of Pentonville in order to act as bait for psycho artist Franco and later got him out permanently on a technicality.
To distract himself from Brenda, Sonny focused his attention on Claire. Diane called him out about using Claire to compromise the prosecution. Diane was always suspicious of Claire's agenda and berated Sonny for trusting her. After seeing Sonny and Brenda kiss, Diane confided in Alexis that the wrath of a scorned Claire would not be pretty. As Diane predicted, Brenda and Sonny renewed their relationship. To Diane's surprise, Claire elected to stay in Port Charles and told Diane and Alexis that she wanted to join their firm. Diane cautioned Claire to think carefully about what it would be like to live in the same town as Sonny and see him with another woman.
Brenda and Dante were being sued in a wrongful death suit over the killing of a henchman of an international criminal known as the Balkan. Brenda had shot the henchman in self-defense. Theo Hoffman was sent from Diane and Alexis' New York office to defend them. Theo had a very abrasive personality, and Jason didn't like the way he was treating Brenda. Diane explained that Theo was getting Brenda ready to testify, and she would do the same thing.
Jason was afraid that Brenda would crack. If the truth about Brenda and Dante's hiding the body of the Balkan's son, Alexander, were revealed, Dante could lose his badge and Michael's parole would be in jeopardy. Over Diane's strong objections, Jason ordered Spinelli to do a background check on Theo. Diane refused to condone an illegal investigation of a colleague. After all the cases she'd handled for Jason, Diane resented his lack of faith in her and her firm, and she did her best to distract Spinelli from the search.
Spinelli had decided to write the adventures of the Jackal P.I., and after overhearing Diane composing what sounded like a steamy romance novel, he thought she would be the perfect collaborator. Eager to explore her creative roots, Diane relished the assignment.
Lucky wanted Spinelli to investigate a possible connection between Jerry Jacks and Alexander, the Balkan's son. Diane explained that because Alexander was killed years before, the trial had to be cold. Lucky called her on the fact that because she was Jason's lawyer, she knew that Brenda had killed Alexander and Dante had covered it up. Because of attorney/client privilege, Diane was not able to discuss the case. She did wonder if Lucky had reason to believe that the Balkan was someone other than Jerry. Lucky hoped that it was Jerry because then Siobhan and Brenda would be safe. Diane questioned Lucky about Siobhan's intentions to stay in the States if the Balkan were caught.
Diane delivered an unsolicited pre-nuptial agreement to a surprised Sonny. Sonny called Diane on planning his divorce when he'd only just gotten engaged. Diane explained that it was a precautionary measure and wondered if he was having doubts. Sonny reminded Diane that he paid her to be his lawyer not his shrink. Diane assured Sonny that she only wanted what her clients wanted. Ideally, Sonny and Brenda would live a long and happy life. If not, Diane wanted to be sure that his assets were protected. She asked Sonny why, if he was as concerned as he said he was about the safety of the people close to him, he was he going through with his wedding to Brenda when the Balkan was a serious threat. Sonny told her that Brenda thought he was worth the risk.
Diane was in the throes of creative storytelling when Carly arrived, looking for Spinelli. Carly blurted out that she had to stop Brenda and Sonny's wedding. She wanted to make sure that their conversation was covered by attorney/client privilege. Diane confirmed that Jason's generous retainer assured that it was. Carly admitted that she might have circumvented a few laws when she obtained information that Brenda and Dante had not only slept together but they had a child, which meant that Sonny was marrying the mother of his grandchild. She needed Diane's help in getting her hands on the copy of proof. Diane was incredulous that Carly wanted her to help in blowing her prize client, Sonny's, wedding apart.
Diane chalked Carly's information up as one of her crazy schemes -- twisted but genius. Diane was intrigued but needed the facts. She admitted it would be incredible material for one of her books. Carly explained that she had put Spinelli on the case, and she produced a document that stated that Dante had signed away all legal rights to Brenda's child. Because Carly had obtained the document illegally, she needed Diane to get her legal proof. Diane reminded Carly that Carly was asking her to get evidence against her most lucrative client.
Although Diane admitted that Carly painted a horrifying scenario, Diane wondered why she would risk getting fired. Diane agreed to help but only after she swore Carly to secrecy about Diane's involvement. Spinelli had covered his knowledge of the facts by telling Jason that he and Diane had started to write a series of books about the adventures of the Jackal P.I. Jason warned Diane that if he appeared in the book in any way, shape, or form, Diane would risk suing herself on Jason's behalf.
Diane had unknowingly placed Brenda at risk when she hired an associate named Theo Hoffman to work at the law firm. He was specifically brought on to defend Brenda and Dante in a wrongful death lawsuit. Theo was actually the Balkan and kidnapped Brenda on her wedding day to Sonny. After she was rescued, her son was revealed to be alive and Diane prepared the paperwork that legally connected Brenda to her son. In the process, Diane angered Sonny when she advised Brenda not to name Sonny as a legal guardian because he had done enough damage in the lives of his own children.
Sonny was not pleased with Diane's outspoken words of caution to Brenda and he warned Diane she had crossed the line as his attorney. Diane was not concerned and instead focused on the promotion of the book she had written with Spinelli. Soon after, Diane decided to make some changes in her life and she ended her relationship with Max and left the law firm. Diane pursued another form of writing when she was hired as a gossip columnist by the former mayor Prescott Floyd.
Eventually Diane returned to her former career as a criminal defense attorney but she no longer represented Sonny. Instead, Alexis remained on retainer for the Corinthos organization while Diane handled matters for a variety of clients, including some of Sonny's enemies. Her decision to represent the artist Franco angered several Port Charles residents. Diane ignored the negative views and instead focused on the potential earnings she would receive when Franco's artistic muse returned. She and Franco were rumored to be dating and they shared a kiss but Diane's heart remained with Max. She rushed to be by his side after he was seriously injured in a shootout and they reconciled shortly after.