Trust me, you'll want to check it out. It's a pretty long read the first time (took me two days to read it all), but it's definitely a fanfic worth reading, and this is coming from a guy who normally doesn't read fanfics. If you like, here's a link to the story. [link]
She's one of those OC ponies that stand out in the fanfic. I will dare say that Nyx is deserving of being part of canon should the right people come across the story. Her character and story arc is complex and lovable from the start.