A lot of fans were undoubtedly disappointed with Captain Phasma in Star Wars: The Force Awakens since she had nothing to show for herself despite being one of the coolest-looking people in the movie. For someone who was supposedly a badass, she was very quick to give-up and lower the shields to the Starkiller base. So what gives?
Thanks to the new Phasma novel, we now have a better understanding on Phasma's motivations and where she truly stands with the First Order. Star Wars Explained on Youtube elaborates:
So as it turns out, Phasma is not really known for her loyalty. Pretty much like Boba Fett, she's a very selfish character, and the reason why she was so quick to betray the First Order was because she was only looking after herself. It was even revealed in the comic how well she covered her tracks so the First Order wouldn't be able to tell that she was the one who lowered the shields on the Starkiller.
In all honesty, I think this was just the expanded universe's way of fixing plotholes in the Star Wars movies. The same thing happened to the original trilogy, and that's why it makes sense that Han Solo would brag about doing the Kessell Run in parsecs, and Ponda Baba's arm wasn't cauterized when Obi-Wan cut it off with his lightsaber.
Despite everything, reviews for the Phasma novel were positive. I'm just hoping we get to see more of her selfish nature come out in Star Wars: The Last Jedi. The Lucasfilm story group should try their best to avoid these messy plotholes.
Star Wars: The Last Jedi comes out Dec. 15.