In the fanfiction, it could be that a curse has turned Sesshomaru into a baby. Kagome stumbles upon him in this state. She decides to take care of him, despite his initial protests (even as a baby, he has his pride). As she nurses him back to health, she discovers new aspects of his personality. When he finally returns to his normal form, their relationship has changed, and there is a new level of closeness between them.
One possible story could be that Kagome somehow finds an abandoned baby in the feudal era. Sesshomaru, being the powerful demon he is, initially shows little interest. But as Kagome tries to care for the baby on her own, Sesshomaru starts to notice her determination and kindness. Eventually, he might offer some form of protection to Kagome and the baby, perhaps out of a newfound respect for Kagome.
There could also be humans who are afraid of the baby's mixed heritage. They might view it as an abomination and try to get rid of it. These humans could be part of a more superstitious group that believes demons and humans should never mix.
Perhaps the baby was left behind by a group of traveling humans or demons. Sesshomaru would be reluctant to get involved at first, but Kagome's motherly instincts kick in. She takes the baby in and Sesshomaru, out of a sense of duty or perhaps an unspoken bond with Kagome, decides to help. They then embark on a journey to find the baby's family or a safe place for it. Along the way, they face challenges that test their relationship and their beliefs.
Well, she could try to find a way to return him to his normal form. Maybe she'll search for some ancient magic or consult with a powerful sorcerer in the feudal era.
One great fanfiction where Kagome finds a baby Sesshomaru could be 'Kagome's Unexpected Discovery'. In this fic, Kagome stumbles upon a baby Sesshomaru in a forest glade. The story then delves into how she decides to take care of him, despite their previous enmity. It's a heartwarming tale of an unlikely bond forming between the two.
I'm not sure of a specific titled fanfiction exactly like this, but there could be many on platforms like Archive of Our Own. You can search for tags like 'Sesshomaru', 'Baby Kagome', 'Found Family' to narrow down the results. It's likely that in such a fanfiction, there would be a lot of cultural clashes as Sesshomaru is from a very different world than Kagome, which could make for some interesting plot points.
In fanfiction, the baby could inherit Sesshomaru's grace and strength. It could have a lithe body like him. However, it would also have Kagome's human charm. Its eyes could be a mixture of Sesshomaru's intense gold and Kagome's brown, creating a really unique and alluring look. And perhaps it would have some sort of special power that combines Sesshomaru's demon abilities, such as his speed and regeneration, with Kagome's spiritual powers.
Well, it could be a heartwarming story where Sesshomaru takes on the unexpected role of a protector for the baby Kagome.
Well, in fanfiction, it often involves bending the original storylines. Maybe some writers see the potential for an interesting dynamic between Sesshomaru's cold and powerful nature and Kagome's warm - hearted and determined self. Their interactions during their adventures could gradually lead to a deeper connection that eventually results in a relationship and having a baby. It's all about exploring different character combinations and creating new stories.
Perhaps Sesshomaru sees some value in Kagome. Maybe he realizes that she has certain powers or knowledge that could be useful to him in the future, so he decides to save her from Inuyasha.
Protection is a major theme. Kagome is usually portrayed as a protector, and Sesshomaru, with his great power, also gets involved in protecting the baby. There might also be a theme of growth. The characters, especially Sesshomaru, grow and change as a result of the situation with the baby. They might become more open - minded or develop new values.