Spike isn't the manliest of dragons but he's ok with that. In fact, he actually accepts his more feminine side and starting to show his more appreciation towards more cutesy things. He still considers himself a guy, but Spike just feels more open about his feelings.

However, this greatly upsets the grand deity of dragons: Lord Smarg. Seeing a dragon being so girly around ponies greatly offends him so and having Spike be a male makes it worse. And so, seeing that the young dragon wants to be more feminine, Smarg decides to give him what he wants.

And also give her the full experience of being female.

Contains: Gender Bender, Dick Growth, Futanari, Furry, Nakadashi (Cumming Inside), and dealing with gender identity