Thinking back on the idea that sprites represent the Platonic “geists” of their associated heroes, when we consider that both Roxy and Calliope contain “Nepeta-ness”, it starts to look a lot like the theory put forth in Plato’s Symposium that humans, having been created with two heads and then split into two, search for a romantic partner who literally completes them; Roxy and Calliope both contain different parts of Nepeta, and they attract each other because these different aspects of Nepeta-ness want to join together into a whole Nepeta.

Which makes complete sense in Homestuck, because that’s exactly what the cherubs are: “two-headed” beings who split in two upon reaching maturity, and spend their lives seeking out a mate who matches their missing half!