Pandora's Box

Lulu (Louise Brooks) is the mistress of a respected, middle-aged newspaper publisher, Dr. Ludwig SchÃ¶n (Fritz Kortner). One day, she is delighted when an old man, her "first patron", Schigolch (Carl Goetz), shows up at the door to her apartment. However, when SchÃ¶n also arrives, she has Schigolch hide on the terrace. SchÃ¶n breaks the news to Lulu that he is going to marry Charlotte von Zarnikow (Daisy D'ora), the daughter of the Minister of the Interior. Lulu tries to get him to change his mind, but when he discovers the disreputable-looking Schigolch, he leaves. Schigolch introduces Lulu to Rodrigo Quast (Krafft-Raschig), who wants her to join his new trapeze act.
The next day, Lulu goes to see her best friend Alwa (Francis Lederer), who happens to be SchÃ¶n's son. SchÃ¶n is greatly displeased to see her, but comes up with the idea to have her star in his son's musical production to get her off his hands. However, SchÃ¶n makes the mistake of bringing Charlotte to see the revue. When Lulu refuses to perform in front of her rival, SchÃ¶n takes her into a storage room to try to persuade her otherwise, but she seduces him instead. Charlotte finds them embracing.
A defeated SchÃ¶n resigns himself to marrying Lulu. While the wedding reception is underway, he is disgusted to find Lulu playfully cavorting with Schigolch and Quast in the bedchamber. He gets his pistol and threatens to shoot the interlopers, but Lulu cries out not to, that Shigolch is her father! Schigolch and Quast thus escape. Once they are alone, SchÃ¶n insists his new wife take the gun and shoot herself. When Lulu refuses, the gun goes off in the ensuing struggle, and SchÃ¶n is killed.
At her murder trial, Lulu is sentenced to five years for manslaughter. However, Schigolch and Quast trigger a fire alarm and spirit her away in the confusion. When Alwa finds her back in the SchÃ¶n home, he confesses his feelings for her and they decide to flee the country. Countess Augusta Geschwitz (Alice Roberts), herself infatuated with Lulu, lets the fugitive use her passport. On the train, Lulu is recognized by another passenger, Marquis Casti-Piani (Michael von Newlinsky). He offers to keep silent in return for money. He also suggests a hiding place, a ship used as an illegal gambling den.
After several months however, Casti-Piani sells Lulu to an Egyptian for his brothel, and Quast blackmails Lulu for financing for his new act. Desperate for money to pay them off, Alwa cheats at cards, but is caught at it. Lulu turns to Schigolch for help. He has Geschwitz lure Quast to a stateroom, where she murders him. Schigolch, Lulu, and Alwa then flee.
They end up living in squalor in a drafty London garrett. On Christmas Eve, driven to prostitution, Lulu has the misfortune of picking a remorseful Jack the Ripper (Gustav Diessl) as her first client. Though he protests he has no money, she likes him and invites him to her lodgings anyway. Schigolch drags Alwa away before they are seen. Jack is touched and secretly throws away his knife. Inside however, he spots another knife on the table and cannot resist his urges. Unaware of Lulu's fate, Alwa deserts her, joining a passing Salvation Army parade.
Plot notes

There is no real explanation given in the film for Schigolch's relationship with Lulu, but it has been suggested he is or was her pimp.[1] In the source plays by Frank Wedekind, Schigolch is possibly Lulu's father.

Question: Who is Lulu's rival?
Answer: Charlotte.