Your acute observation that ERIS spelled backwards is SIRE, and your inference to the effect that there is sexual symbolism here, have brought me to some observations of my own.
ERIS spelled fore-part-aft-wards is RISE. And spelled inside out is REIS, which is a unit of money, albeit Portugese-Brazilian and no longer in use. >From this it may be concluded that Eris has usurped Eros (god of erotic love) in the eyes of those who read backwards; which obviously made Eros sorE. Then She apparently embezzeled the Olympian Treasury and went to Brazil; whereupon She opened a chain of whorehouses (which certainly would get a rise from the male population). I figure it to be this in particular because MADAM reads the same forwards and backwards. And further, it is a term of great respect, similar to SIRE.
And so thank you for your insight, it may well be the clue to the mystery of just where Eris has been fucking around for 3125 years.
FIVE TONS OF FLAX!