This story ties in to Rising Star

Diamond doesn't know why she keeps having the nightmare. She doesn't even know what that thing she's running from is.

And she definitely doesn't know about the ancient power she's helping to wake up a little more every time she has it.

Midnight's worried. Trapped in his star, there are a lot of things he can see but not do anything about. And any time he uses the knowledge he gains as a Wishing Star to help his old friends, there's a price. With the threat that's coming, that price will be far too high.

And then he finds her. A young filly on the precipice of Darkness, about to fall. And she's the answer to his problem.

So the Alicorn of Hope gives a filly some gifts. Freedom from her recurring nightmare, the ability to help her friends sealed carefully away in a box she can't open yet, a riddle that makes no sense, and a cryptic warning so vague she's convinced he got it from a fortune cookie.

And Faust help Equestria, but Diamond's our only chance.

Sex tag is primarilly for a rather large misunderstanding. There are/will be a few small references to things that actually happened in backstories, but no details.