Christine Daae is the love interest in every adaptation of The Phantom of the Opera
When she was a little girl, Christine's father passed away. Before he died, he told her that he would send her an Angel of Music to be her spiritual guide.
When Christine became a part of the Paris Opera, she was mentored by an unseen entity that she assumed was The Angel of Music. After the lead singer Carlotta was given a hoarse throat by this "angel", Christine was given her part. Her performance attracted the attention of her childhood friend Raoul, who resolved to marry her.
Christine kept Raoul at arm's length to avoid angering the Phantom, who would invite her into his secret lair as a way of earning her trust. When Christine saw the Phantom's true form was a masked man, she was disappointed at first, then horrified after seeing his true face. The Phantom kept Christine on an even shorter leash than before, demanding that she be his wife after her next big performance. When the Phantom kidnaps Christine, Raoul and an enigmatic Persian chase after them. The Phantom tortures them until Christine gives the Phantom something he never had before: compassion. The Phantom is so touched by Christine's selfless nature that he releases Raoul and the Persian. Christine would then marry Raoul.
Raoul de Chagny
Christine and Raoul had known each other since they were children. Being from an aristocratic family, Raoul was determined to make Christine his wife. When he found out that Christine was too committed to her craft, he was angered and became aggressive towards her, but stopped when he found out about the phantom's twisted hold on her. Even though Raoul was initially after Christine as a prize, by the end of the story he has proven both to Christine and himself that he does care for her.
Erik the Phantom
Erik's facial disfigurement made him an outcast to the rest of the world. To alleviate himself from the pain of loneliness, he commited himself to the opera. When he came across Christine, he decided to teach her as a way of leaving his mark. After a while, Erik fell in love with Christine. His isolation had made him obsessive over her and he tried to drag Christine down into the depths with him, unable to comprehend her own freedom. When Christine showed Erik some kindness, he realised how wrong he was to hold her prisoner and sets her free.