Little bit of a warning before reading! It has sex, as if it was not obvious, and there is quite the build up before the actual sex.

Canterlot, the place where the rich and mighty live and reign over their land and wealth. The posh and elite considered the most proper and glamorous amongst all the cities of Equestria. And where there is wealth, there is also dark secrets that is shared with no one. Some secrets that even the Princesses don't know about. Sex and power is what take the reigns when the sun lowers below the horizon.

Some actively seek these places out for relaxation from their perfect day jobs, often the most innocent amongst the people of the day are the most dirty at night. Almost like they take on whole new personalties. And there are some that by chance come upon these places and either immediately regret it or they are enraptured by the sex and money of the night.

Twilight will soon decide what she will do with this knowledge.

Told ya that I would write more Rarilight
Now while the cover is anthro, the fic is humanized. Fully. And no it does not take place in EQG universe.
Original pic (uncropped) by FoxInShadow[

Thanks to zurvan for the suggestion for the title
Some honorable mentions:
VitalSpark "In Rare Form"
The Atlas Complex "A Rare Occurance"
And Mysticalrainboom "A Rare Sight"