Honestly just a really fun series. I'm very amused that the author only started turning up the dial labeled homosexuality at the end of the second book but kept turning it up til by the end the two leads are kissing on board the ship while both looking like young men

yes technically deryn "is a girl" but by the end of the third book subtext becomes text that she has no plans in the foreseeable future of being seen as a woman by anyone if she can help it and that alek is attracted to her not in spite, but perhaps because, she passes as a tall muscular young man easily

Also honestly I respect building your sci-fi alt history around a "okay what if the way the early 20th century goes the armenian genocide and the rise of the nazis never has to happen" premise

usually alt history stories have more genocide not less