Exactly how steamy is this story?
PG-13
Lord of Light is heavily based on Hindu mythology, and like any good mythology, there's a healthy dose of the sexy sex to be had in its stories. When you're an all powerful deity whose nine-to-five involves toying with the forces of nature itself, you don't give prudence much thought when planning your Friday night.
With that said, Zelazny keeps the more comely scenes within the realm of PG-13:
He followed her from Heartbreak to Despair, his pulse quickening in his throat, and when he had laid her bare on the couch and placed his hand upon the soft whiteness of her belly, he knew […] the feeling to which that room had been dedicated filled him, even as his desire mounted within him and he upon her—there came a loosening, a tightening, a sigh, and the ultimate tears burning to be shed. (5.142)
See what we mean? The scene lacks the graphic details we'd associate with a deity-themed issue of Hustler, and it's not a gratuitous sex scene for the sake of just having a sex scene—the language used to describe this vertical ballet characterizes the participants and bares their complex relationship for the reader to see. Ending with the "tears burning to be shed," suggests how doomed these two characters are.
So, sex scenes? Absolutely. Gratuitous? Hardly. In fact, they are necessary if we are to really understand the psyche of nearly immortal humans being trapped in the mindset of a god.