This story was a product of The 3AM Epiphany (the only writing exercise book I recommend, by the way) when I was doing a daily "boot camp" - an exercise a day. This was one of the very first exercise, to write a story purely in the form of commands ... implied second person. I decided to go the route of orders given to a young person being initiated as a priest - and it took a (for me) very dark turn.
I'm not sure when I decided to create a very ambiguous, pitiless goddess, but it definitely shaped the tone. For more - read it.