One common theme is the struggle between good and evil. Since Nightmare Rarity is a darker version, there's often a battle within her or against other characters. Another theme is the power of friendship. Even in a fanfic about a villain - like character, friendship can play a role in her development. Also, the theme of transformation is common, whether it's her changing from Nightmare Rarity back to normal Rarity or evolving into something new.
One plot idea could be Nightmare Rarity trying to take over Equestria's fashion industry with her dark and edgy designs. Another could be her forming an unlikely alliance with other villains to achieve a common goal. Maybe she has a redemption arc where she realizes the error of her ways through the friendship of a kind pony.
Another theme is her relationships. Fanfics often explore her friendships with the other ponies in Ponyville, like how she interacts with Twilight Sparkle or Fluttershy. For example, there are stories where she helps Fluttershy gain more confidence through fashion. Also, her rivalry with other fashion - minded ponies can be a theme, showing her competitive side in the fashion world.
No, chastity - themed fanfics are not popular in the MLP fandom, especially when it comes to Rarity. Most fanfics focus on more common themes like friendship, adventure, or character growth.
It's not popular at all. Popular MLP fanfics tend to be those that explore the core themes of the show, such as the magic of friendship, the challenges the ponies face, and their growth. 'Rarity butt inflation fanfic' is a very niche and rather unappealing concept to the general MLP fan base. It goes against the more common and positive types of stories that fans usually look for, so it's not likely to be something that has a large following.
I haven't read this specific fanfic in detail. But generally, in fanfics about Nightmare Moon's return in My Little Pony, they often explore themes like redemption, the struggle between good and evil, and the impact on Equestria. It might show how the ponies deal with this new threat and perhaps how Nightmare Moon's character develops during her return.
Another interesting mlp rarity fanfic is 'The Mysterious Rarity'. This one takes a more mysterious turn. Rarity discovers an old attic in her boutique filled with strange items. As she starts to explore, she uncovers secrets about her family's past and how it relates to her love for all things rare. It has an engaging plot and really makes you think about Rarity's backstory.
The 'team - up against a common enemy' trope is also popular. They might face a villain who is trying to disrupt the harmony of Ponyville. Rarity uses her wits and Rainbow Dash uses her speed and strength. In the process, they discover new sides of each other and their friendship deepens.
Often, there's the theme of self - discovery through love. Rarity might learn more about herself and her own desires while falling in love. And sometimes, there are adventure - related themes. Maybe Rarity and her love interest go on a quest together, and during that journey, their relationship develops. There can also be the theme of sacrifice, where one character has to give up something for the other in the name of love.
I'm not entirely sure as it seems like a very specific and rather odd concept. 'MLP FIM' stands for 'My Little Pony: Friendship is Magic'. But 'rarity butt inflation fanfic' sounds like a made - up and strange fan - created story that likely involves some sort of comical or perhaps inappropriate (if taken too far) inflation concept related to the character Rarity. However, without actually reading it, it's hard to say exactly what it's about.