The other immortality books that I have read are either about gods and goddesses, or about humanity trying to discover it, but Origin is different because Pia was born into it, and it wasn't her fault to have it in the first place. SPOILER. And at the end of the book, she fights to get rid of it, something I have never encountered before.
The characters in the story were great, but you could see that there was something fishy about them from the very beginning. Pia was a good heroine, and she was written in the way that was exactly like her upbringing, caged and brainwashed. Pia was a bit snotty, and being told that she was perfect all the time didn't really help. Although she become less stuck-up, some of her snobbishness lingered throughout the entire book. I really didn't feel anything about Eio, he seemed nice, but we never really got to see him much, and he was just that guy in the forest for most of the book, nothing really happened. Although I was happy the love didn't overwhelm the story, I think there was a bit to little. If Pia had more love to fight for, she would of been a stronger character. The one other important character in the story was Dr. Harriet. She was great, even though she hardly knew Pia, she was nice, willing, and taught Pia how to be free.
I think there was too little description in the story. There was barely anything about the inside of Little Cam, other than the horrors of what was going in it's depths. The rainforest had a bit more, but not much. We only ever got to see vague details about what it looked like, a good description has all the senses in it, not just one.
Origin is a great book about immortality, one very different to a lot of other ones. The characters are brilliant, and the plot is just perfect. This book teaches us about freedom, and what it is to being truly human.