One idea could be that the OC is a healer who comes across Bankotsu's gang. Bankotsu is initially skeptical of her but as she heals his wounds, he starts to develop feelings. Another could be the OC is from a rival clan but falls for Bankotsu's strength and charisma, leading to a Romeo - Juliet - style relationship within the Inuyasha universe.
Perhaps the OC is a powerful priestess in hiding. Bankotsu stumbles upon her hiding place. At first, they are at odds as he wants to use her power for his own gains. But over time, he sees her as more than just a means to an end. Their relationship develops as they face common enemies in the Inuyasha world, like demons that threaten both of them.
One idea could be that the male OC is a powerful mage from a far - off land. He crosses paths with Inuyasha and the gang while on a quest to retrieve a powerful magical artifact that has been lost in Feudal Japan. His magic skills could either complement Inuyasha's fighting style or cause some initial clashes due to differences in their approaches.
First, start with their initial meeting. It should be a bit rocky. Bankotsu is a tough character. So, the OC needs to have some sort of quality that intrigues him, like being fearless or having a unique power. Then, as they interact more, show small moments of connection. For example, the OC might share her food with Bankotsu when they are on a journey together, and he starts to see her kindness.
One idea could be creating an OC who is a powerful miko from a far - off land. She could have unique powers that even Kagome doesn't possess, like the ability to control the elements in a different way. For example, she can make ice sculptures out of thin air that can be used as weapons against demons.
Another plot could be Sango getting injured and Inuyasha having to take care of her. It would show his softer side and how their relationship might change as he nurses her back to health. This could also include some flashbacks to their past experiences that made them who they are.
One idea could be that Inuyasha and Kirara have to team up to protect a special magical item from a powerful demon. Along the way, they discover new abilities in each other and form a deep bond of friendship that might turn into something more.
Another idea is that Bankotsu gets injured and Kagome, with her kind heart, decides to nurse him back to health. During this time, they have long conversations about their different worlds. Bankotsu shares his tales of battle and Kagome tells him about her own world and the friends she has left behind. This leads to a mutual respect and a budding relationship.
An interesting OC mate could be a human with a special connection to the spiritual world. She can see the spirits that Inuyasha sometimes misses. Their story could involve her helping Inuyasha understand the deeper mysteries of the spiritual realm. They might meet when she is being chased by a minor demon and Inuyasha saves her. This event sets off a chain of adventures where they fall in love while uncovering secrets about the world they live in.
One plot idea could be that the reader is hesitant to tell Bankotsu about the pregnancy at first because she's not sure how he'll react. But then she finally does, and he surprises her with his enthusiasm. Another idea is that they face some challenges during the pregnancy, like a difficult prenatal diagnosis, but they support each other through it.
Well, a possible plot for Koga x Inuyasha mpreg fanfiction is that a mysterious artifact they come across has some sort of fertility - enhancing magic. Inuyasha accidentally activates it and becomes pregnant. Koga is confused but also excited. They then have to find a way to keep Inuyasha safe during the pregnancy. Maybe they seek help from a wise old priestess who is hesitant to get involved at first. Or perhaps they face a rival who wants to harm Inuyasha because of this unique situation, thinking it will make Koga weak.
One idea could be a scenario where Inuyasha and Naraku are forced to team up against a greater evil. Maybe a powerful demon from another realm arrives and threatens to destroy everything they both hold dear. They start off distrusting each other but gradually learn to work together as they realize they have no other choice.