Jason and Marceline is a sequel to Space Station Seventh Grade, published four years earlier. The later book contains the same characters, but they are two years older. In Space Station Seventh Grade, Jason and Marceline meet.

At first they are not at all friendly. In fact, Jason imagines that he detests Marceline. But before the book ends, they discover that they are greatly attracted to one another. That attraction matures even more in Jason and Marceline.