In Batman: Arkham Knight, five characters were been infected by the Joker's blood. The resulting mutation was slowly altering their minds and bodies, giving them physical and mental traits similar to the Joker. One of these individuals, Christina Bell, was heavily inspired by a version of the Joker from an alternate universe: Bianca Steeplechase. This version of the Joker had a strong rivalry with Barbara Gordon instead of Batman for one simple reason: She killed Dick Grayson.
Bianca Steeplechase debuted in Batman: Thrillkiller #1, by Howard Chaykin and Dan Brereton in 1997. Born on Earth-37, Bianca was masquerading as the wife of Gotham City's mayor, but was merely using that as a cover for her illegal activities. In reality, she was a sadistic criminal known as the Joker. She even managed to kill Robin with a poison kiss, leaving a bereaved Barbara Gordon behind.
Bianca was interested in her own gain, planning to push a new type of drug known as nicotics, "nics" for short, into the city. The resulting profits would have made Bianca obscenely wealthy and finally give her true independence from the men she used as a cover for herself.
And much like the original Joker, Bianca even had a romantic relationship with Harley Quinn. Though in this universe, the love between the two of them was genuine, spurred on by their mutual sadistic pleasures. As Bianca put it, everything she did, she for love.
Within Arkham Knight, Christina Bell's motivations were very similar to Bianca's. In fact, Christina was heavily inspired by Bianca's role as the female Joker.
The Joker's blood had differing effects on those who weren't fortunate enough to receive the cure in time. In the most general sense, it was slowly altering them until the Joker was in complete control of their minds and bodies. But there was a psychological component to the illness that meant some aspects of the Joker became more prominent in their hosts as opposed to all of the Joker's traits. The effects still drove them mad, but they had different reasons for behaving the way they did. For example, one of Christina's fellow infected, Johnny Charisma, displayed the Joker's showmanship, becoming a lethal attention hog.
In Christina's case, she was overwhelmed by the Joker's obsession with Batman. When he caught her and placed her in quarantine to try and devise a cure for the infected, Christina developed Stockholm Syndrome, coming to believe she was in love with Batman. But like Bianca, her reason for doing anything now was for love. In this case though, it was an unreciprocated love brought on by a physical illness.
The two even have a similar starting point. Prior to her to infection, Christina had a successful career in finance. She was a board member for Queen Industries and even had ties to Stagg Enterprises. Likewise, Bianca used her position as the mayor's wife to afford herself protection and luxury while she worked on her schemes. Both women were actually fairly influential before their darker natures were exposed. Though in Christina's case, this was an unfortunate tragedy.
And both women ultimately met their demise as a result of their actions as well. Ironically, their deaths occurred shortly after meeting Harley Quinn. Bianca had already committed herself to Harley, but her subsequent battle with Barbara resulted in her death by drowning. And in Arkham Knight, when Harley liberated the infected, Christina was recaptured by Batman, only to be killed by another of the infected. So it seems even Bianca's death inspired the ending of Christina Bell's story.