A fan fiction could start with Tristana and Leona being sent on a mission to investigate some strange occurrences in a forest. There, they encounter Ahri who seems to be involved in the mystery in some way. Later, Caitlyn arrives as she has been tracking Ahri. But instead of arresting her, they all realize they need to work together to solve the mystery.
Another idea for a fan fiction is a story of friendship. Suppose Ahri is lost in a strange land. Tristana, Caitlyn and Leona find her. At first, they are a bit suspicious of Ahri because of her fox - like appearance. But as they get to know her better, they become friends and together they face various challenges like dangerous monsters and difficult terrains.
A simple alliance in this fanfiction could be that Baiken helps Naruto with her sword skills. Naruto is mainly a ninjutsu user, so her sword - based combat knowledge could be a great addition to his fighting repertoire.
Another aspect in a fanfiction could be their cultural differences. Naruto comes from a world of ninjas with strict honor codes, while Shego is from a more modern - ish world with different moral values. This could lead to many comical or thought - provoking situations. For instance, Naruto might be shocked by Shego's casual attitude towards stealing or using underhanded means in combat. However, as they spend more time together, they begin to see the value in each other's perspectives. They might even influence each other's ways of thinking and acting, with Naruto making Shego more empathetic and Shego teaching Naruto to be a bit more flexible in his approach to problems.
A fanfiction could also explore the idea of Starkiller and Ahsoka meeting in a post - Empire world. Starkiller, having broken free from his Sith past, and Ahsoka, who has seen so much of the galaxy's turmoil, could join forces to help rebuild and protect the newly - emerging peaceful systems. They would have to overcome their differences, as Starkiller has a more aggressive style while Ahsoka is more in tune with the Jedi's peaceful ways. But their shared goal of a better galaxy could bring them together. They could start by training a new generation of Force - sensitive beings, combining their unique teachings to create a more balanced approach to the Force.
In fanfiction, Neji and Sakura could form an unlikely alliance against a common foe within the Hidden Leaf Village. This could be due to some political intrigue where they have to trust each other despite their different personalities.
Another interesting alliance could be between Ron and Keroberos. Ron, with his love for food, might be constantly bribing Keroberos with treats to get information about the Clow Cards or to ask for his help in some comical situations. Keroberos, being a bit of a glutton himself, would be easily swayed by Ron's offerings.
A simple fanfiction plot could be that Peter accidentally stumbles into Wakanda while on a mission. Shuri finds him and at first is suspicious. But then she realizes his good intentions. They start to exchange ideas about technology and hero - work.
In some fanfictions, there could be a time - travel element. What if Draco and Hermione are sent back in time? They might have to work together to ensure the future they know doesn't change. This could lead to some interesting character development as they are forced to rely on each other in a completely different time period, and they may see each other in a new light as they face challenges together.
Perhaps the fanfiction focuses on a parallel universe where Snape, Harry and Lucius are all on the same side from the start. They are part of a secret group that is trying to reform the wizarding world's education system. Their different perspectives - Snape's strictness, Harry's compassion and Lucius' cunning - combine to create a powerful force for change.
Well, in such a fanfiction, they could team up against a common enemy. Maybe an ancient dark force that has been awakened in both their times. Their combined knowledge of magic from different eras would be a great asset.