- "What did I ever do to you, Nygma? What did I do that compels you to come here with your endless notes and suggestions and riddles? My god, the riddles!"
- —Kristen Kringle to Edward Nygma[src]
Kristen Kringle was the record keeper of the Gotham City Police Department. She later became the girlfriend of Edward Nygma and after discovering that he had killed her ex-boyfriend Tom Dougherty rejected him, causing him to kill her by accident.
Admired by Edward Nygma
As the official record keeper of the Gotham City Police Department, Kristen encountered Edward Nygma when he went searching for any files the GCPD had on the past Spirit of the Goat killings. She later became frustrated with him when he re-organized all of the files in the records annex, with the intention of "helping her".
Nygma continued his pursuit of Kristen, leaving her a riddle cupcake with an apparently live bullet in it on her desk. Kristen returned the token in no uncertain terms. When Nygma later approached her and told her he thought she was beautiful, Kristen was flustered and didn't know how to respond. Detective Arnold Flass, however, instructed Nygma, to back off and stop bugging her. As Nygma left but was still in earshot, Kristen thanked Flass, calling Nygma weird.
Kristen was later given a poem by Nygma that was found by Flass and his coworkers, having a good laugh at Nygma's expense. Kristen later goes to see Nygma at his office and apologizes, telling him that Flass found the poem. Nygma attempts to compliment Kristen, but she stops him and then leaves. She later witnesses the arrest of Arnold Flass.
She later is seen crying in her office as Nygma tells her he is suspended. She feels sympathy and wishes something could be done giving him an idea as Ed gives her a broken pencil. Despite her initial repulsion, when Nygma is reinstated she points out that he owes her a pencil, giving him cause to seek her out again.
After Arnold Flass was released from prison Edward Nygma went to see Kristen Kringle in his lab and tried to warn her about his release and how he is such a bad influence. Kristen appreciated his concern but says that she realizes that there are far more better men than Arnold Flass and then leaves causing Edward to smile.
As Edward Nygma tries to ask her out to dinner with flowers behind him Kristen reveals that she has dinner plans with her new boyfriend Officer Tom Dougherty who meets Nygma as the guy who likes riddles. Tom appears to like Nygma and then leaves with Kristen who feels sympathy for Edward as she looks back at him with regret.
She is seen making out with Tom in the annex as Edward passes by with a watermelon basket as Tom leaves. Edward comes to her for the files Detective Gordon wants as she gets them he notices a bruise on her arm from Tom as she says it was an accident and she said stuff wrong to back Nygma off to not get involved and later mentions she needs work on the files.
As Edward Nygma secretly gets rid of Dougherty's body Kristen knocks on the door to get the case Hendricks files. He comes to open the door and gets the files as Kristen looks on the dead body wondering how he died as Nygma says accidental death by a saw. He hands her the files and then asks him about Tom's whereabouts as Ed says he doesn't know. He later pushes her off to matters on his own. She gets a Dear Jane letter from Officer Dougherty which was secretly planned by Nygma, who checks on her to see if she is ok. She is angry and goes for a drink. Nygma tells her to read between the lines and sees that the first letter of each line spelled out Nygma.
As Nygma is looking for files Kristen comes to him, revealing she had solved his clue. Nygma claims it as a coincidence, saying he knows nothing about this. Kristen is confused and leaves to dig deeper, as Nygma smiles until she shuts the door.
When The Maniax attack the GCPD, Kristen was so petrified with fear, that she is unable to even duck for safety. This leads Nygma to dive at her and knock her to the ground, out of harms way. Following the siege of the station, Nyma approaches Kristen as she is giving a statement to officers, and tells her to have dinner tonight. He holds up a piece of paper that says Chez Moi and tells her to meet him at 8:00. Grateful for his rescue of her, Kristen accepts while sharing she'd like that. Nygma smiles and assures that she will. Kristen is a little disappointed when she finds out Nygma invited her to his place, instead of a restaurant like she expected. Nygma apologizes for not being up front and says he likes to cook for guests. Kristen accepts this, so she stays and they have a good time.
Kristen exits the room for a minute, and comes back to find Nygma saying leave me alone, and Kristen thinks he is talking to her. Taking offense, she gets ready to leave. Nygma stops her and explains he has a voice in his head that keeps him in line because he is a klutz. Kristen says she understands since she thinks everyone has a voice like that. She asks what his voice said, as Nygma said it was mad at him for spoiling the mood. Kristen says her voice is saying they can get back there. Nygma and Kristen go to kiss, but their glasses collide. They both laugh and take their glasses off, so they can properly kiss each other.
They become a couple not long after. Very soon, Kristen and Ed had a double date with Leslie and Jim.
While on a date, Kristen takes her relationship with Nygma to the next level. Sometime after in Nygma's bedroom, Kristen brings up her fear of Tom Dougherty returning, having previously threatened to kill her if he saw her with another man. With no more excuses, Nygma reveals that he killed Dougherty. At first, Kristen laughed, believing it was a joke, but as Nygma told her that he was serious, she started backing away from him when he showed her Dougherty's badge. Kristen started to pack and called him a psychopath, believing he was stalking her during her relationship with Dougherty. However, the door was locked and she couldn't escape, despite hitting Nygma with nearby items. She then was pinned to the door and was inadvertently choked to death by Nygma, who was concurrently reassuring her that he was not a complete monster and only killed Dougherty in self-defense because of his actions and that he loved her. As Nygma realized she was dead, he yelled in agony and grief.
When Nygma was unconscious, the darker figment of his imagination gained control of his body and took her corpse to the GCPD Police Department where Nygma would later find her severed hand inside a vending machine. A clue leads him to Leslie Thompkin's examination room, where he finds Kristen's body inside a drawer. Leslie Thompkins nearly sees her body but is quickly lured out by Nygma for a drink of coffee. When Nygma returns, his darker ego asked him how it felt to kill her, to which he responded that it was beautiful as his dark side merged with his physicality. Nygma starts to cut up Kringle's body. He later took her cut up corpse to a woodland to be buried.
Nygma told Leslie Thompkin's that Kringle reconciled her relationship with Dougherty and has left Gotham, and feigned being distraught.
Nygma is eventually tricked into revealing the location of Kringle's corpse by Jim Gordon and gets arrested by the authorities and imprisoned at Arkham Asylum. It is unknown what happened to her corpse after Nygma's arrest.
A year after her death, Nygma comes across a woman named Isabella while shopping for wine and mistakes her for Kringle. The pair enter into a relationship, although Nygma began to fear that he would end up murdering her. When the pair had lunch together, Isabella put on a pair of glasses resembling Kringle's, causing Nygma to panic and flee to the bathroom where he was met with a hallucination of Kringle in the mirror. The illusion proceeded to taunt him and say he will kill her too. After some convincing from Penguin, Ed was certain that in order to protect Isabella, he would need to break up with her, much to Penguin's delight as he too harboured feeling for Ed. However, since he could not bear to do it himself, he asked Oswald to do it for him.
After a stern warning to stay away from Ed by Penguin, Isabella realised that he also had feeling for him and was certain that Ed would never and could never hurt her. After Penguin left, she formed an idea and studied old photos and newspapers of Kristen and dressed exactly as she did, even dying her hair. When Ed stopped by, she emerged from the bathroom, much to his shock, which caused him to try and leave. She then firmly grabbed him and forced him to look at her. As he calmed down, she reached for his hand and put it around her neck and just as it seemed as though he would snap and kill her, the two shared a passionate kiss and proceeded to sleep together.
However, after their night together, Penguin learned of their reunion and ordered Gabe to sabotage the breaks on her car. Whilst on the way to a librarians conference, Isabella came across a train crossing and attempted to break but was unsuccessful. Whilst heading full speed towards the track of an oncoming train, she yelled for help but was eventually silenced by the train blasting into the side of her car, killing her. Her death drove Ed to turn on Oswald and destroy his empire with the help of Barbara Kean. He managed to successfully do so, even managing to shoot Oswald in the stomach and throw him into the river.