Definitely don't read the most recent one, Translation Space. It's some very bad "I like you but I don't know how to say it!" YA-vein tropes and the climactic scene is, essentially, people walking around a circular hallway a couple times.
It was so bad it caused me to re-read the original three, and I realized that only the first was one was any good.
It was so bad it caused me to re-read the original three, and I realized that only the first was one was any good.