A time - travel plot could also be interesting. The Reader, along with America and England, get sent back in time to a significant historical event. They have to work together to make sure the event unfolds correctly, while also dealing with their own personal growth and the development of their relationships in this new historical context.
There are many great non - lemon 'America x Reader x England' fanfictions on Archive of Our Own. You can search for tags like 'Gen' (general audience) along with the character names to find suitable ones. Some might focus on their cultural exchanges or friendship dynamics in a more platonic way.
One idea could be a story where the reader is a foreign exchange student in Canada. They meet Canada and initially mistake him for someone else. As they get to know each other, they discover Canada's unique culture, like maple syrup festivals or ice hockey games. They bond over these shared experiences and develop a deep friendship that could potentially turn into a romantic relationship over time.
One idea could be that the reader is a Quincy and they initially clash with Ichigo due to the historical differences between Soul Reapers and Quincies. But as they face a common enemy, like a powerful Arrancar, they start to understand each other and form a bond. Another could be that the reader has the ability to see into the future in the Bleach universe and warns Ichigo about upcoming threats, and they work together to prevent disasters.
The fem oc could be a time - traveler who has knowledge of future events. She tries to prevent a great disaster from happening in the Naruto world. Naruto at first is skeptical of her but as they start to work together and she shows him proof of future tragedies, he believes her. Their relationship develops as they race against time to change the future.
One plot idea could be a story where the reader is a new recruit in the Akatsuki. Deidara and Sasori are assigned to train the reader in different aspects of being a member. Over time, a strong bond of friendship forms between the three, and they have to work together to face a common enemy within the Akatsuki who is trying to undermine their positions.
Another idea is that the reader is a foreign exchange student in the Hetalia world, and China is assigned to be their guide and mentor. The story could follow their journey as the reader adjusts to the new culture, with China helping them understand the traditions, language, and social norms. This would be a great way to explore their relationship in a non - sexual and educational context. It could also include some humorous moments like misunderstandings due to cultural differences.
A great plot could be that the reader is a journalist trying to uncover the truth about the revolutionary army. Sabo is assigned to keep an eye on them to make sure they don't expose any sensitive information. But as they interact more, they realize they have a lot in common and start to fall for each other. Or perhaps the reader is an artist who meets Sabo during a cultural exchange event organized by the revolutionary army, and their shared love for art brings them together.
One idea could be a mystery - solving plot. The reader and Masky team up to solve a series of strange occurrences in their town. Along the way, they learn more about each other, their strengths and weaknesses, and develop a deep bond based on mutual respect and shared goals.
One plot idea could be the male reader being a new student at Ouran High School and gradually becoming friends with the host club members through a shared interest, like a love for music or art. The story could focus on how they bond over this common passion and how the male reader helps the host club in unexpected ways, for example, by suggesting new themes for their events.
Another plot could be that the reader is from a different dimension where Pokémon don't exist in the same way. When they end up in Ash's world, Ash helps them understand and adapt. Along the way, they develop a deep friendship as the reader discovers the joys and challenges of the Pokémon world. It's a unique take on their relationship that doesn't involve any adult themes.