Young Nictis had one dream: to serve his hive by becoming an Infiltrator, the most vital and vaunted role a changeling could aspire to. To hide in plain sight among the other species, blending in, while gathering the vital emotional energies that fueled his people. Few were deemed worthy of the dangerous job. He was one of the few nymphs selected for training, in the hopes that one of them would develop the skills needed to be entrusted with such a treacherous task.
But when a training expedition ends in tragedy, Nictis finds himself thrust into the role not to serve his hive and people, but to preserve his own life. Separated from the hive, alone, he must put what little training he has to the test. He must blend in with the hive's greatest source of food, and it's most dangerous enemy: the ponies of Equestria.
This is seriously the best fanfiction I have ever read. It is as good as and even better than some of the fantasy I've read. Don't blow it off just because it is My Little Pony Fanfiction. It's phenomenal.
One of the few things I remember from high school English class is that Great Expectations is a "bildungsroman", which is a novel following the growth of a character from childhood through to full adulthood and maturity.
I hated Great Expectations. But I love this story.
The protagonist, Nictis, starts out as a young monster-in-training learning how to be a Changeling Infiltrator. He views ponies as nothing but prey, to be decieved and have their love sucked out and destroyed for the good of his hive. Then a training accident suddenly leaves him stranded alone in Equestria, with no way home, and he has to find his own way without any outside guidance.
I won't sugarcoat it, Nictis is not a nice person. He has been trained from his first breath to be manipulative and selfish toward ponies and he learned those lessons well. But a bildungsroman is a story about the growth of a character so it would be pretty pointless if he didn't have a lot of growing to do at the outset.
I really came to feel for Nictis. I can't say much about the trajectory of his life without spoiling it - and I really think the best part of this story hinges on the uncertainty Nictis has about his role in life so I definitely won't be doing that - but it's well worth getting invested in this character so you can ride his highs and lows.
Knowledge of the Friendship is Magic TV series is necessary for this novel to make sense, up to and including "A Canterlot Wedding."