I've read 'Leviathan' a few times now, and honestly, the main plot is a lot to unpack. It's set in an alternate 1914 where the world is split between the 'Clankers,' who use massive walker machines, and the 'Darwinists,' who have fabricated living creatures as weapons. The story follows two teenagers: Alek, the heir to the Austro-Hungarian throne on the run after his parents are assassinated, and Deryn, a girl disguised as a boy serving on the British airship Leviathan, which is a giant living whale-beast. Their paths collide when the Leviathan crashes in the Swiss Alps, forcing them into an uneasy alliance to survive.
For me, the key themes are the obvious ones—the clash between technology and nature, but also identity and duty. Alek's whole life is about living up to a legacy he didn't choose, while Deryn constantly has to hide who she is to pursue her dreams. There's also this undercurrent about the absurdity of war, shown through the lens of this bizarre, biologically engineered world. It's not just a steampunk adventure; it makes you think about how we define progress and what we're willing to sacrifice for it.
I always come back to the friendship that develops between Alek and Deryn. It's the heart of the book, navigating all that mistrust from their opposing worlds.