Maybe in the fanfiction, the human child has some special abilities that are unknown in Equestria. For example, the child can communicate with a certain type of magical creature that the ponies have always been curious about. So the ponies adopt the child in order to learn more about these abilities and how they can benefit Equestria. Fluttershy could be especially gentle and helpful in taking care of the child.
One idea could be that the ponies in Equestria discover a lost human child in their magical forest. They decide to take the child in out of kindness. Twilight Sparkle could use her magic to create a special living space for the child. And the other ponies like Pinkie Pie would throw parties to make the child feel welcome.
A plot could involve a human child who has a special ability to communicate with all animals in Zootopia. The child is then recruited by the Zootopia police to help solve a mystery that involves a group of animals that seem to be acting strangely. This could lead to an adventure where the child discovers new aspects of the city and its inhabitants.
One idea could be that a human stumbles into Equestria and meets Luna. Luna is intrigued by this strange being from another world and they go on adventures together, exploring the magic of Equestria. The human could teach Luna about human culture and in return, Luna could show the human the wonders of pony magic.
One idea could be a human with unique skills, like being a great artist, arriving in Equestria. The ponies are fascinated by the human's different art style and the human has to learn about Equestrian art in return. For example, the human could introduce the concept of abstract art to the ponies, while learning about the magical paintings in Equestria.
Maybe a Pikachu adopts a human child. The Pikachu is part of a group of Pokemon that live near a human village. The child was abandoned, and the Pikachu takes it in. They go on adventures together, with the Pikachu protecting the child from other wild Pokemon and teaching it how to communicate with different Pokemon species.
One idea could be that a human child gets lost in the Pride Lands and is adopted by a lioness. The child grows up learning the ways of the lions, facing the same challenges as Simba did, like dealing with Scar's evil plans. Another could be that the human child has a special power, like being able to communicate with all animals in the Pride Lands, and uses it to bring peace between the lions and other species. Or perhaps the human child is a descendant of an ancient tribe that has a connection to the Pride Lands and must fulfill a prophecy to save the kingdom.
One idea could be that the Godzilla sees the human child in a dangerous situation, like a collapsing building during a battle, and decides to protect the child. It could then form an unlikely bond with the child, who is not afraid but rather curious about the giant creature.
One idea could be that the human child gets lost in the Pride Lands and is found by Simba. Simba then takes on the responsibility of protecting the child and teaching it the ways of the jungle. Another plot could involve the human child having a special ability, like being able to communicate with the animals in a unique way, which helps in solving a big problem in the kingdom. Or perhaps the child is a descendant of an ancient tribe that has a connection to the Pride Lands, and its presence awakens something long forgotten.
An interesting concept could be a male human OC who is a talented artist. He gets inspired by the colors and beauty of the MLP world and starts creating art that has a magical effect on the ponies. His art could help solve problems in Equestria, like bringing back the lost colors of a fading meadow.
In this type of fanfiction, a great plot could be that Carlisle and Esme discover Bella has a prophetic dream ability. This ability makes her very valuable in the vampire world as she can foresee potential threats. However, it also makes her a target. Carlisle and Esme must then train Bella to control her power while also keeping her safe. Additionally, the family dynamics could change as Bella becomes closer to them. She might start to change some of their long - held beliefs about humans and vampires, and this could lead to internal family discussions and growth.
In some stories, Bella could be the key to uniting different vampire clans. Since she's adopted by the Cullens, she might be seen as a symbol of a new way of vampire - human coexistence. This could lead to other vampires either trying to use her or trying to protect her from those who want to use her for their own gain.