Erique Claudin is the primary antagonist/anti-hero of Phantom of the Opera (1943 film), loosely based on Erik in Gaston Leroux's 1910 novel The Phantom of the Opera. In the original script of the movie, Erique was Christine's father, but that idea was dropped and Erique's interest with Christine remained unexplained. A lot of other things were also different from the original Erik character. Like that Erique wasn't deformed from birth, that he got his face destroyed by acid
Erique Claudin has been a violinist for the Paris Opera House for 20 years now. He has secretly been paying for Christine DuBois' music lessons. One day, the owner of the Paris Opera House calls for a meeting with Claudin as he thinks he is the one who has been causing the discord in the violin ensemble. Claudin explains that he has gotten pain in the left fingers recently which affect his playing, and is dismissed from the orchestra because of it.
Claudin has almost no money now. Claudin goes to Signor Ferretti, Christine's music teacher, and begs him to continue to instruct Christine despite not getting payed, until Claudin gets a new secure position. Ferretti refuses. Claudin tells him he has written a concerto, and asks him once again to consider teaching Christine free for a while, and get paid for it later. Ferretti once again refuses. Erique is sure that Pleyel and Desjardins will publish it and give him a substantial advance.
Claudin goes to Pleyel & Desjardins to let them have a look at it while he's in the waiting room. An employee of Pleyel who quits for the day comes out and Claudin asks him about his manuscript. The employee claims that he doesn't know anything about it. Claudin sneaks in, intent on getting his script back. He interrupts Pleyel & his secretary etching images. Pleyel orders his secretary to give Claudin his concerto. She can't find it. Claudin gets mad and worried. Pleyel, now tired of Claudin, tells him that an employee probably threw it in the wastebasket where it belongs. Pleyel tells him good night and walk back to his etchings. Claudin hears his music being played on piano. Franz Liszt plays it while talking to an employee. The employee says he has been trying to convice Pleyel for years to publish Claudin's work. Liszt responds that Pleyel will publish this. Unfortunately, Claudin cannot hear their conversation, he hears only the music being played and believes Pleyel is stealing his music, publishing it under his own name. Claudin, in a torrent of rage, chokes Pleyel to death. When Pleyel falls to his demise on the floor, his secretary throws the acid, used for the etchings on Claudin.
Claudin, with a lot of pain, and now hunted by the police, goes into the sewers and makes his way to the Opera House. He gets a mask to hide his disfigured face. He steals food when he has the opportunity. He also steals the master key, which opens all 2500 doors in the Paris Opera House.
He starts his reign on terror on those who stand in the way of Christine's career and those who stand in the way for his goals. His first victim is Biancarolli. Aware that Christine is Biancarolli's stand-in, he drugs Biancarolli so Christine will stand in for the show's remainder. Later, Biancarolli is furious with what has happened. She believes that Anatole did it for Christine. The opera house crew convinces her to forget about it as it could hurt the Paris Opera House, as well as herself. Biancarolli agrees under certain conditions. She demands that if she is to forget that she was drugged tonight, then everyone should forget Christine's success that night. They reluctantly accepts her decision with dismay from Christine, but Anatole seems even more mad about it than Christine. Erique who has found out about this is really annoyed with Biancarolli now. Later, he shows up in her dressing room and kills her.
Anatole spots the Phantom running away and decides to run after him which leaves him in a dangerous situation which has him losing his track on him.
Next concert Raoul decides to have another person take Christine's role. However Christine does show up because she couldn't stay away. Erique decides to release another torrent of terror on the people and brings down the large chandelier on the audience and cause panic and chaos to spread.
As the audience and the crew flee, Erique lures Christine that he is from the police and is delegating Raoul and takes her down to his lair, pursued by Anatole, Raoul and the other police officers. Christine realizes he's not from the police and wants to get away. Erique says that they will have it wonderful down here. Christine will sing for him, and he will play. He also says that the people of the Opera House has corrupted her against him, that's why she's afraid. Liszt plays Claudin's concerto and Erique who hears it plays along. The first song is "Lullaby of the Bells" and Christine who heard it in Provence and made her rendition of it can't understand how this Phantom could play it and claim it to be his. He urges her to sing and she does. But after a while when she stands beside him she tears off his mask.
She backs away in terror of the sight of Erique's deformed face. Raoul and Anatole walks in too and Raoul accidentally fires a shot. While Christine, Raoul and Anatole make their way out, Erique is buried under a pile of rocks.
In the end however, the mask and the violin is placed in front of the rocks and some of the rocks were moving. Some believe this could indicate that Erique put the music behind him and was going for a new beginning.
The original script had Claudin being Christine's real father. Even scenes were filmed but were then cut because of the incest theme. Some romantic interest seemed to be implied from Claudin which is partially why the producers changed their mind. So in the current version, Claudin's affection for Christine is not fully explained. His feelings for her seems both romantic and paternal.