As the daughter of a federal agent, Claire moved around often as a child. At age eleven, she developed a slight crush on her seventeen year-old distant cousin, who taught her how to deep-sea fish. This cousin was killed shortly afterwords while trying to prevent a store robbery. The shooter was acquitted on a technicality, and Claire vowed to uphold the law as a prosecutor ever since.
Storylines
Federal attorney Claire Walsh is brought to Port Charles by powerful businessman Jasper Jacks to prosecute mobster Sonny Corinthos, who is on trial for his late wife Claudia's murder. Jax wants to put this longtime rival in prison for good. Claire immediately clashes with Jax's wife (and Sonny's ex-wife) Carly, and with Sonny's lawyer, Diane Miller.
Claire sees prosecuting Sonny as an opportunity to boost her career and soon resorts to ethically-questionable tactics in order to get a conviction. After witnessing Sonny go off on a murderous tirade over how his estranged daughter, Kristina Davis, had recently dropped assault charges against Ethan Lovett (it is revealed shortly after that she was in fact assaulted by her boyfriend Kiefer Bauer), Claire uses it to her advantage by having Johnny Zacchara, Claudia's younger half-brother (later revealed to be Claudia's son) and Sonny's longtime rival, lie on the stand and claim that Sonny regularly beat up and abused Claudia. Sonny loses his temper, calling Claudia despicable names and shouting that she got what she deserved; unfortunately, Kristina witnesses the whole thing, and by the time anyone notices her there, the damage is already done. When Sonny's longtime friend, Robin Scorpio, is called in to testify, she initially paints Sonny in a positive light by telling how he had helped to found the hospital's HIV wing, but Claire turns things around by forcing Robin to admit that Sonny had demeaned Claudia and swore that it would be the last time she ever lied on the day of the murder.
As Claire prepares to push Sonny to the limit to get a conviction, she enlists Sonny's long-lost son Dante Falconeri, who was recently shot by Sonny, to put the first nail in the mobster's coffin. Despite Claire's faith that he will tell the truth, Dante perjures himself on the witness stand, claiming that he accidentally shot himself. Claire, suspecting that Dante's younger brother Michael Corinthos has information about Claudia's death, then begins pressuring the cop to find his recently-disappeared brother and bring him back to Port Charles to testify against Sonny. Dante refuses to do so, so Claire takes Sonny's youngest son, Morgan Corinthos, out of school under false pretenses without Carly's knowledge to question him; Dante's attempts to defend Morgan only result in him being arrested for contempt of court. When it is Carly's turn to testify, she brings her infant daughter Josslyn with her; Carly's convincing, albeit false, testimony greatly weakens Claire's case against Sonny. Meanwhile, Dante has finally broken down and gone to search for Michael, locating him and bringing him back to Port Charles. However, Dante doesn't turn Michael in right away, leaving him alone long enough to escape.
Moments before the jury is about to deliver a verdict, Dante walks in and exposes Michael as Claudia's true killer. Upon discovering that Jax knew all along, Claire is furious that he misled her and her superiors from the start and vows to bring him down with her if the case tanks her career. After Michael confesses to the crime, Judge Carroll unfairly gives Michael a sentence of five years in Pentonville Adult Correctional Facility to teach everyone in the courtroom a lesson. Claire, like everyone else involved, feels guilty for her role in the tragedy; she had always believed that it was Sonny who killed Claudia and never expected that it was Michael. To protect Michael, Jason Morgan, Sonny's lieutenant and best friend, makes a deal with Claire and is sent to prison along with him. When Sonny and Diane put their heads together to find out how to get Michael out of Pentonville, Claire decides to help them, explaining that she was after Sonny and not Michael and she believes that the judge most likely would have been more lenient if it weren't for Claire and Diane's courtroom antics.
Claire and Jax then put their heads together to figure out how they can get Michael out of jail. With little luck, she goes to Dante and asks him to help dig up dirt on Judge Carroll. They plan to use the judge's dirty laundry to blackmail him into changing his verdict. Eventually, Dante convinces the judge to release Michael on the grounds that he live with Dante and have minimal contact with Sonny.
Claire meets Dante's partner, Lucky Spencer at the park with his two sons, Cameron and Jake. Claire reveals that she has always wanted children and, in a sort of emotional meltdown, tells Lucky that her "biological clock is ticking." Lucky cautions her that raising children isn't as easy as it looks, but that making his sons happy is what is really important. Claire tells him that she is sorry for "unloading" on him but says that if he ever wants anymore children, to call her. Not long afterward, she asks Lucky to team up with her in an effort to put Sonny and mobster Johnny Zacchara behind bars once and for all. Lucky agrees to help, and after they have spent more time together professionally, Claire asks Lucky out on a date.
In the meantime, in an attempt to revive her career after the embarrassing Michael Corinthos debacle, Claire makes it her mission to put Sonny in prison, permanently. Sonny offers to help her in putting Johnny away, by pushing Johnny into taking action against him. Claire agrees, but she later confides in Lucky that she is merely playing Sonny, and plans to double cross him; Sonny is a "bigger win" than Johnny.
Claire also finds herself drawn into the return of the crazy psycho Franco, who has reappeared in Port Charles to resume his feud with Jason. Jason makes a deal with Claire and Dante and is temporarily released from Pentonville to draw Franco out of hiding. After causing havoc throughout Port Charles for many weeks, Franco departs town again and Jason is sent back to prison. However, on August 16, 2010, Claire acts on a loophole she had secretly inserted in Jason's plea bargain to have him permanently released from Pentonville to gain Sonny's trust; though her superiors are anything but pleased that she put Jason back on the streets, Claire makes it clear to both them and Sonny that she will build her career up her own way.
On July 27, 2010 Claire discovers that Warren Bauer went on a rampage and tried to murder Kristina at the hospital out of revenge for the death of Kiefer, whom Alexis accidentally killed in a hit and run on after he assaulted Kristina again on April 2, only to be killed by Mac Scorpio. Claire is not entirely surprised by this news and reveals that Warren has been calling her twice a day for the past month and pulling whatever tactic he can think of to try and pressure her into reopening the investigation into Kristina's abuse. Claire subsequently asks Sonny to be her sperm donor, but he refuses.
The pair's love-hate relationship intensifies, and Sonny is surprised when she tape records a conversation with him and proposes to use it as evidence that his later shooting of Johnny was done in cold blood. However, she is soon rightly convinced that the shooting was self-defense, and after Sonny and Johnny proctor a peace agreement, Claire and Sonny engage in a casually romantic relationship; though Claire soon realizes that she has genuine feelings for Sonny, Sonny secretly admits to Dante that he is only romancing Claire because he is on the rebound. Claire removes herself from the government's ongoing case against Sonny due to conflict of interest. Many people warn her that this is a foolish idea, but Claire responds that it is her choice.
In September 2010, she accompanies Sonny on a tropical romantic getaway.
In early October 2010, Sonny breaks up with Claire because of Brenda. Claire is bent on getting revenge at Sonny for leaving her. To this end, she confronts Jason in Sonny's offices, threatening to send Michael back to Pentonville unless Jason testifies against Sonny. Sonny arrives to do damage control, but it is not until Jason decides to call Diane in that Claire admits that she was bluffing and never had any intention of turning Michael in.
Claire and Sonny get back together late October. Claire and Sonny's romantic moment is cut short when they learn Brenda has been brought in to the PCPD. Claire chooses between career and love when Ronnie hands her proof of Sonny's culpability in the car-bombing. Sonny demands Claire tell the truth, but Claire ultimately disposes of the evidence upon discovering that Ronnie had obtained it without a warrant. When Kristina arrives to talk to Sonny, Claire allows her to do so and watches as the two finally make peace with one another.
Sonny ultimately decides to break things off with Claire to help her salvage her career and because of his longtime love for Brenda, but she does him one last favor. Deciding that Michael has been punished enough, she convinces the judge to lift the restrictions on Michael's release, allowing Sonny and Michael to see one another at any time. Claire reassures Sonny that she has accepted that he has moved on and tells him to follow his heart.
On November 23, 2010, Claire meets up with Diane and Alexis, asking to join their firm because her superiors are planning to transfer her to Alaska. Though Alexis thinks it would be a good idea, Diane initially refuses. However, when Claire asks a second time, Diane agrees that she will allow it if she really wants the job, but believes it would be best for her to leave town. On January 17, 2011, Claire visits Sonny to inform him that she is now partners with Diane and Alexis at their firm. She hasn't been seen since January 21, 2011.