Blue Sophie, also known as the Red Hindenburg, is a former prostitute, whose significance in the series is to serve as a fake Margot Langer, which gets her involved with Hans Georg Schuwald and those surrounding him.
One day while out at a bar, Blue Sophie encountered Halenka Novakova, who was, at the time, using the alias of Margot Langer. It's unknown whether the two were familiar with one another before that point.
After a couple drinks and shedding a few crocodile tears, Sophie was able to get Halenka to spill out her life story, including all the details of her fling with businessman Hans Schuwald. A few months later, Halenka was the victim of a phantom killing, so Sophie decided to use the name Margot Langer, along with the information she obtained, to make a considerable profit.She went to Schuwald and confessed to him that she was the "real Margot Langer," with evidence of knowing her past to back it up. Schuwald was very much aware that the woman who approached him was a fraud, but the mere idea of being able to atone for his sins was enough, so he began showering her with money. The action became frequent, and Schuwald started visiting her every evening to pay his dues. "Margot Langer" also became a popular person for the students claiming to be the son of Schuwald, and was paid visits by Johan Liebert and Edmund Farren, as well as Lotte Frank and Karl Neuman.
After Johan led Farren to his execution and latched onto Karl, Blue Sophie started to draw conclusions. She realized that Johan was responsible for not only the student's death, but also Halenka's, Richard Braun's, and others who were close to Schuwald. Hoping to get some hush money, she sent a letter to Johan ordering him to come meet with her.
In response to the blackmail, Johan had Roberto form a relationship with the woman. When he went to pay her a visit and she revealed to him all the details she knew regarding his scheme, Sophie then instructed him to name the price he'd be willing to pay in order to keep her quiet. As a reply, Johan informed her he no longer had any interest in Schuwald and got up to leave. At the same time, Roberto, Sophie's "boyfriend," entered the room and shot her.
Blue Sophie is a self-assured woman who could be regarded as slightly arrogant. She often takes amusement in making jokes which are, apparently, found humorous by no one other than herself. Sophie is intelligent enough to trace the murders surrounding Schuwald back to Johan, but not smart enough to know how to use the information correctly, as indicated when she attempts to blackmail him.
Although the fact that she learned of Johan's scheme and then asked for hush money is never stated directly, it is heavily implied during their conversation in episode thirty-four.
"Names don't mean crap, right Johan Liebert?"