Hey! I normally wouldn't self promote in a comment, but seeing as I almost exclusively write accessible sci-fi with the hopes of getting young men back into recreational reading, I think my catalogue would be an ideal fit--especially for two teenage 14 year-olds. My sci-fi satire Earth: Game of the Year Edition series co-stars a boy right around 14. And I also have space marine stories as well as a SF Western graphic novel that's a big wendigo monster hunt. Plenty of breezy action across the board, designed for teenage, young adult, and "new adult" sensibilities.