Well, it could be about Spike's adventures as a pony. Maybe he discovers new magical abilities that are unique to ponies. He might make new pony friends and go on quests with them in Equestria.
The fanfic could center around Spike's transformation into a pony and how he adjusts to his new form. He could struggle at first with things like flying or using pony magic, but then gradually master them. He may also face some prejudice from other ponies who are not used to a dragon-turned -pony, but through his kindness and determination, he wins them over. And perhaps he gets involved in a big event in Ponyville that only he, with his dragon - turned - pony perspective, can solve.
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.
Well, it could be that Spike feels unappreciated in Ponyville. Maybe he's tired of always being seen as just Twilight's assistant. So he runs away to find a place where he can prove himself and be his own dragon.
In the fanfic, it might also be about Spike having some sort of problem, like he accidentally gets into trouble with a magical artifact. Big Mac, being the reliable and steady pony he is, steps in to help Spike figure out how to fix the situation. This could involve them going to visit Twilight Sparkle for advice and along the way, they face various challenges that test their bond and also show their individual personalities.
One possibility could be a story where Spike sacrifices himself to save his friends. Maybe there's a great danger in Equestria, like a powerful dark magic that only Spike can stop because of his unique dragon abilities. He might use his fire to counter the dark magic but in the process, exhausts all his energy and dies. His friends are left to mourn his loss but also remember him as a hero.
One possible plot could be that Spike discovers some ancient magic in the dragon lands. This magic starts to manifest in a strange way, causing him to grow wings. At first, he's scared and confused, not knowing how to use them. But with the help of his pony friends like Twilight, he starts to learn how to fly. Along the way, he might face some challenges from other dragons who are jealous of his newfound ability.
Spike MLP Fanfic is a type of fan - made literature that focuses on Spike in the context of My Little Pony. Fans write these stories for a variety of reasons. Some might be huge Spike fans and want to give him more spotlight. Others might want to explore different storylines that could have happened in the MLP world involving Spike. It can range from humorous tales where Spike gets into comical situations to more serious and emotional stories about his place in Equestria and his relationships with those around him.
A possible plot could be centered around Spike's loyalty to Twilight. He discovers a secret that Twilight doesn't want anyone to know. Instead of thanking Spike for keeping it, Twilight blames him for finding out in the first place. This betrayal from Twilight, the one he admires the most, shatters Spike's world. He then has to decide whether to stay loyal or move on.
Well, it could be about Rarity's journey to becoming an alicorn. Maybe she discovers a hidden magic within herself and has to go through a series of trials to transform. For example, she might have to prove her selflessness by using her fashion skills to help those in need in Equestria.
He could meet other dragons. Since he is a dragon himself, it would be natural for him to encounter some of his own kind during his runaway journey. They might teach him about dragon culture and traditions that he doesn't know much about.
Magic gone wrong is a common reason. Maybe a spell that Twilight was working on backfired and accidentally turned Spike into a pony.