Molly and Case, sitting in a tree...

In the novel Neuromancr, the two main characters Case and Molly have an obvious romantic interest in eachother. Since this is a work of science-fiction, Molly is naturally "highly desirable" as well as tough and agressive.

The reason for this is simply the type of audience that was reading this book back in the 1980's. The typical science-fiction fan was a nerdy high-school student whose dream girl must have looked a lot like Molly. Also, other interests of this demographic include sex and drugs which are alo present in the novel.

The tricky part is when Molly leaves at the end. This may have been done for two reasons. First, it leaves open the option of a continuing quest for Case. Second, it avoids the typical "Hollywood" ending that plagues most stories.