I'm not entirely sure as 'abuse' in fanfiction is a very concerning and often inappropriate topic. In general, My Little Pony (MLP) fanfiction should be positive and in line with the show's values. Spike is a character in MLP, and any form of abuse in fanfiction is not acceptable in a healthy fandom.
Well, 'mlp' stands for My Little Pony. Spike is a character from that franchise. A 'fanfic' is a fictional work written by a fan. However, the 'diaper' part makes it a bit strange. It could potentially be a very unique and niche fan - created story where Spike has some sort of adventure or situation that involves diapers. Maybe it's a comical take on the character, or perhaps it's a more serious exploration in a very different kind of story setting, but again, this is all speculation without actually reading the fanfic.
In a 'evil spike mlp fanfic', it might be that Spike has been influenced by some external dark force. This could lead to him betraying his friends and working against the values of friendship that are so central to My Little Pony. The fanfic could delve into his motives, like if he feels unappreciated or overlooked, and then show how his evil deeds play out and whether there's any chance for redemption in the end.
With the dragons, Spike's status could be different. Dragons that used to look down on him might now be either more respectful or more hostile out of envy. Among the ponies, Spike would become even more of a novelty. Some ponies might ask him for rides or to help them reach high places. His relationship with Rarity could also be affected. She might be inspired to create new outfits for him to match his new look with wings.
Well, Pinkie Pie is also a likely main character. She would be the one to throw a big 'Welcome to Pony - hood' party for Spike. She could also introduce him to all the fun and wacky things about being a pony. Rarity could be involved as well. She might take it upon herself to give Spike a makeover in his new pony form, making him look dashing and stylish among the ponies.
One common theme is self - discovery. Spike often starts off not realizing his potential as a superhero and then gradually discovers his powers and what he can do. Another theme is friendship. His friends in the MLP world usually play a role in his superhero journey, either supporting him or getting saved by him.
Friendship is a very common theme. Since Spike and Fluttershy are both beloved characters in MLP, many fanfics focus on how their friendship develops. For example, they might help each other overcome their fears or insecurities.
There's also 'The Adventures of Human - Spike'. It could be about Spike being transformed into a human - like form and going on a journey. He might discover new powers or abilities that come with his new form while also dealing with the emotions and relationships that are unique to the human experience.
Yes, there are plenty of non - inappropriate Spike MLP fanfics on DeviantArt. Many focus on Spike's role in the My Little Pony world, his friendships, and his various adventures. For example, there might be fanfics about how Spike helps his pony friends solve problems or his experiences during special events in Ponyville.