The Halcyon Universe, Book 2
Heat Factor: Literally they have sex in the very last scene
Character Chemistry: I am flustered because she’s so cute!
Plot: Danya kidnaps Amy. Amy kidnaps Danya. Danya’s twin kidnaps Amy. Danya rescues Amy. Plus intervening adventures. Also includes: a giant science mystery, a terrorist rebel organization, and pirates. And dragons.
Overall: Fun, rip-roaring space adventure with a dollop of romance.