The Naraku would be a likely kidnapper. He is always plotting against Inuyasha and trying to get his hands on the Tessaiga. Kidnapping Inuyasha would be a way for him to either steal the sword or find a way to break Inuyasha's spirit so that he can no longer oppose him.
A common plotline is that a main character like Kagome is kidnapped by a powerful demon and Inuyasha is the only one who can save her. He has to use his strength and the power of his sword. Another is when Inuyasha accidentally kidnaps someone due to a spell or misinformation.
Another reason might be revenge. There could be a character who has a grudge against Inuyasha or someone close to him. So, they kidnap him to make him suffer or to use him as bait to draw out his friends. For example, if there was a demon whose family was slain by Inuyasha in the past, they might kidnap him for revenge.
One popular 'Inuyasha kidnapped' fanfiction might be where Kagome gets kidnapped by a demon and Inuyasha has to rescue her. It often involves a lot of action and Inuyasha using his sword, Tessaiga, to fight through hordes of enemies to reach Kagome.
Sesshomaru would raise the baby with a combination of discipline and protection. He would protect the baby from any threats, using his powerful abilities. At the same time, he would discipline the baby when it made mistakes, teaching it the ways of the demon world. Inuyasha, on the other hand, would add a more carefree and emotional touch to the parenting, creating a balance in the baby's upbringing.
In fanfiction, the baby could be the key to unlocking some long - lost secrets in the Inuyasha universe. Since Sesshomaru and Inuyasha have such complex histories and lineages, the baby might hold the answers to ancient prophecies. It could also have a special bond with the Jewel of Four Souls, perhaps having a unique way of controlling or protecting it that neither of its parents had. And of course, there would be all kinds of emotional drama as the two brothers - turned - co - parents deal with their new relationship.
Well, his tail in fanfiction could be a sign of vulnerability too. Writers might use it as a way to show his softer side. For example, if someone were to grab his tail, it could make him feel really uncomfortable or even weak. It could also be a way for him to show affection in a non - human way, like wagging it when he's happy around Kagome.
One way is through crossovers. For example, a character from Naruto could accidentally end up in the world of Inuyasha. They might use their unique ninja skills, like Naruto's shadow clones, to help fight Inuyasha's enemies. This would add an interesting dynamic as the ninja abilities are different from the demon - slaying techniques in Inuyasha's world.
One possible fanfiction could be about Inuyasha and Sango going on a quest together. They might face a powerful demon that requires both of their skills to defeat. Inuyasha's brute strength combined with Sango's weapon - handling abilities would make for an exciting adventure.
Some great Inuyasha and Kagome fanfictions include those that focus on their adventures after the end of the series. For example, 'A New Beginning' which shows them building their life together in the feudal era. It has really good character development and stays true to their personalities.