Captain Phasma was introduced in Star Wars: The Force Awakens in 2015 and has made appearances in various Star Wars media since then. One of the most recent appearances is in Star Wars: Phasma by Delilah S. Dawson. The book covers a variety of stories from her time on Parnassos, her home planet, before she joined the First Order.
What Dawson does well with this book is that she tells the story from the perspective of Siv, who spent time with Phasma on their home planet. She tells the story to a rebellion spy, Vi Moradi, who ends up being captured by Cardinal in the First Order. He keeps her his little secret as he tries to find out how to get rid of Phasma. Telling the story that way gives you an outside look at Phasma, instead of seeing everything from her perspective, which would likely come across quite differently.
Having the outside perspective lets you know just how cold and calculating Phasma could be and how everyone around her perceives her. While we don’t get much of her own thoughts on her past, she says enough by the end of the book to make you realize exactly who she is and how accurate the stories about her are.
Throughout the book, you also see what Cardinal thinks of her and they’re supposedly on the same side. Both are trusted within the First Order to train the troopers, but Phasma is a step above Cardinal and that irks him to no end. Dawson portrays every character in the book with a great amount of care and detail. Switching between the stories and the present day gives a little break in the action, but also leaves you wanting to know more about Phasma, which is exactly how Cardinal feels when Vi finished up a story, too.
Overall, this book is a great look into the character and with Phasma appearing in The Last Jedi, I recommend checking it out if you want to know more about her. You can pick up a copy of the book via Amazon.