The Phantom's Guardian (the Phantom of the Opera fan fiction)

Is it fair to keep secrets from your loved one?
Will you do anything to make your loved one happy?
Is love "giving" or "taking, "forgiving" or "acceptance"?

Desiree has always been obsessed with the Phantom of the Opera. On a visit to Paris, she meets a mysterious person who tells her that she could go to the Phantom's world. However, she has to promise not to interfere with the original plot and timeline. She travels in time and pretends to be a boy at the Opéra Populaire , hoping to see the story unfold quietly but fate has other plans for her. A chance encounter with the Phantom led her to work for him and consequently, fall for him. Unable to break her promise, Desiree must watch her beloved takes steps towards his own heartbreak and downfall. What can she do to save him? or will she be able to guard her own secrets?
This story will keep to a mixture of the original events of the POTO play/movie but with new characters, new scenes which I imagined would happen behind the main events, filling in the plot.

@Whovian122003 : "I love this book because it's storyline is unique and its really good read!! I would 100% recommend it."
@Phantomofthe_library: "I love this book. I love the suspense of Erik finding out Desiree's secret and wondering what his reaction will be. I also love the style of the author's writing."
@lover4551am: "I love this book so much I love how she loves Erik but at the same time has to hide those feelings."

Excerpt

"What is your name, boy?" Although the question was not shouted but rather, spoken in a low voice, she could not help but shiver from the threat carried by it and the deep undertone of the powerful voice. "It's De.., De.., " , Desiree stuttered, staring up at the formidable figure in the shadows. Then she remembered that she was supposed to be a boy, and frantically scrambled her mind for a boy's name. Unfortunately, it meant that the first name uttered is the one she's been obsessed with her entire life. "Erik?"