The baby could be an orphan from a nearby village that has been attacked. Kagome stumbles upon the baby while on her travels with Inuyasha. Since she has a big heart, she can't just leave the baby there, so she takes it with her.
Maybe the baby is a reincarnation of an ancient spirit. It's in a human form as a baby, and Kagome is the one fated to find it. The discovery of the baby then sets off a series of events that will change Kagome's journey and her understanding of the spiritual world she is involved in.
It could be a baby demon that has been separated from its pack. Kagome finds it alone and crying. Despite it being a demon, she feels sympathy for it. She then has to deal with the fact that some of the people around her might not be so accepting of a demon baby, but she is determined to protect it anyway.
One popular fanfiction with this premise could be 'Kagome's New Discovery'. It beautifully depicts Kagome's journey after finding the baby hanyou. The story focuses on her attempts to protect the baby and find a place for it in her world.
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.
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.
Well, it could be a heartwarming story where Sesshomaru takes on the unexpected role of a protector for the baby Kagome.
You could also check out some Inuyasha - centered forums. There are often threads where fans recommend their favorite fanfictions, and you might find some good ones about Kagome finding a baby hanyou. For example, the Inuyasha sub - Reddit might have some great suggestions.
Perhaps the baby is a human baby left in the feudal era by some strange magic. Kagome, being from the modern era, has some knowledge about baby care that the others don't. She tries to raise the baby as best as she can, but there are also those who might want to use the baby for their own evil purposes, so Kagome has to protect it from them.
Well, the story could involve Sesshomaru struggling to adapt to raising a baby, facing challenges and learning new skills along the way. There might also be moments of tenderness and growth for both of them as they form a special bond.
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.
A common plot is the development of an unlikely bond. Sesshomaru, who is usually cold - hearted, gradually warms up to baby Kagome. Another plot point could be Sesshomaru protecting Kagome from various threats, like other demons or even humans who might see her as an oddity. For example, he might have to fight off a group of demons who sense her spiritual power even as a baby.
The baby could be an ordinary human baby that has some sort of latent magical ability that Raven senses. She then decides to protect the baby from the human world that may not understand or accept the baby's potential magic, and also from the magical world that might want to exploit the baby.