Kirsten McDuffie was the assistant district attorney who had a playful relationship with Matt Murdock and frequently tried to make him admit to being Daredevil and refused to believe he wasn't.^[2] Over time, their friendly relationship developed into a romantic one and they dated.^[3]

When Matt moved to San Francisco as a result of the voluntary and public revelation of his identity as Daredevil,^[4] Kirsten accompanied him on the trip.^[5] After arriving in San Francisco Kirsten and Matt set up their own law firm.^[6]

They lived together for a while and their relationship seemed unshakable,^[7] until, one night, the Purple Children made everyone forget that Daredevil and Matt Murdock were one and the same. When Matt, still in his Daredevil costume, got home to check on Kirsten, she mentioned Matt wasn't home. Despite initially believing she was joking, he soon realized what the Purple Children had done. Reflecting on this new opportunity, he decided it was best to break up with Kirsten without telling her the truth and return to Hell's Kitchen. Heartbroken, she simply told him to not "let the door hit [him] in the ass on the way out".^[8]

More than a year passed and the two hadn't seen each other again, but when Kirsten heard the news that Matt had been arrested for murder, she called Foggy Nelson (Matt's best friend and fellow lawyer) to offer her assistance with the case.^[9]

They worked tirelessly for days, but Matt decided to speak to the persecutor behind their backs and arrange a deal, confident his neighborhood would be safe after Stark's purchase. As he was ready to accept his fate, Tony called him to announce he had lost the bid on the neighborhood and someone else had bought it. A regretful Daredevil then told Kirsten about the deal and how he was planning to go against it, now that he couldn't make sure the people would be safe with him gone. However, he would change his mind one last time, when Elektra showed up at the court and whispered to him that she was the one that won the auction and that he could trust her to keep everyone safe. To the surprise of Kirsten and everyone else present, Daredevil pleaded guilty to the charge of second-degree manslaughter.^[10]

Despite this, Kirsten and Foggy didn't give up and eventually got Matt freed from jail with no parole qualifications.^[11]