An unlikely way to tell an unlikely story might involve having multiple timelines that intersect in unexpected ways. Or maybe setting the story in a completely unique and unfamiliar setting that challenges the reader's expectations.
It could be due to their personalities. For example, if one is extremely outgoing and the other is very shy. Their different temperaments would create an unlikely combination for a love story. In such a case, they would have to overcome their differences to be together.
Unlikely friends can get along through mutual understanding. For example, if one is a predator - like a wolf - and the other is a prey - like a sheep - they need to understand that they are different from the norm of their species. The wolf might refrain from its hunting instincts and the sheep might trust that the wolf won't harm it. This could start from a situation where they both face a common threat. Like a forest fire that forces them to rely on each other for survival.
It could be their social standing. If they were well - respected in the community, like a church leader or a successful businessperson, people would not suspect them easily. They were probably seen as having too much to lose to engage in such a heinous act. Also, if they had a family and a good reputation, others would find it hard to believe they could be a murderer. Their daily life might have been so ordinary and positive - looking on the surface that no one would think they were capable of taking someone's life.
It could be someone who has a hidden good side, like Draco Malfoy. He was from a Death Eater family but showed signs of not fully embracing the dark side. Maybe in this fanfiction, he decides to protect Hermione for some unforeseen reason, perhaps because he has developed a new understanding of the value of life and friendship.
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 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.
Sometimes it's for character development. An unlikely line can show a character's unique perspective or a turning point in their feelings. For example, if a character says 'I don't believe in this so - called love anymore' after a series of events. It shows a change in their view of love, which can be a crucial part of their development in the story. This also helps to make the character more three - dimensional rather than just following the typical romantic plotline.
The idea of Naruto and Albedo in a fanfiction has a lot of potential. Naruto's ninjutsu could be seen as a form of magic in Albedo's world. Albedo might be skeptical at first but then realize the power Naruto holds. They could bond over their shared sense of purpose, which is to protect and understand their respective worlds. As they journey together, they would face challenges that test their friendship and their ability to combine their different skills.