Leviathan is a steampunk series by Scott Westerfeld. It combines the past with the future, in the setting of World War 1, with fabricated animals, moving land battleships, and armored walkers. It has an amazing level of detail, combined with action and adventure. It also has some very unique aspects, such as showing both sides of the conflict. I would rate this series 5 Stars. I absolutely loved reading it, and I enjoyed every page. For the age rating, I rate it for ages 10+, because of the violence involved, as well as being harder to understand compared to other books.
In this series, Alek and Deryn are the 2 main characters, on opposite sides of the war. Alek, even as prince must flee from his home country after his parents are assassinated, and try to seek refuge, with a loyal band of men to protect him. Deryn must try to fake being a boy to join the Royal Air Service to fight for her country in the war. She wishes to be part of an airship, a massive fabricated beast that flies in the air. Unfortunately, after successfully joining the Royal Air Service, her airship crashes, coincidentally, very close to where Alek and his group of men are in refuge.