Another plotline could involve the two characters facing prejudice from their respective houses or within the wizarding world in general. They then have to fight against this discrimination to be together. This can add a lot of drama and tension to the story. For instance, their friends in their houses might not approve of their relationship at first.
You could also try looking on Tumblr. There are fanfic communities there that might have Hufflepuff x Slytherin lesbian stories. Sometimes, fans post excerpts or links to their fics on Tumblr. It might take some digging around, but you could discover some really interesting and unique takes on this pairing.
One common theme is the idea of overcoming differences. Since Hufflepuffs and Slytherins have very different traits, a lot of fanfics focus on how the two characters can look past those differences and form a relationship.
One possible plotline could be about their initial meeting and the forming of their friendship. Maybe they meet during the founding of Hogwarts and discover that they have different ideas about how to run the school, but also find common ground.
Growth is also a prevalent theme. Both characters grow as individuals within the relationship. The Slytherin may become more empathetic, influenced by the Hufflepuff's gentle nature, and the Hufflepuff may gain more confidence, inspired by the Slytherin's ambition. Their love story is often intertwined with their personal growth.
One great Hufflepuff and Slytherin love fanfic is 'The Unlikely Bond'. It beautifully explores the relationship between a kind - hearted Hufflepuff and a somewhat misunderstood Slytherin. The characters' growth throughout the story as they fall in love is really engaging.
I really like 'Green and Yellow'. In this fanfiction, the author explores how a Hufflepuff's loyalty and a Slytherin's ambition can work together. It has some really interesting plot twists, especially when they team up for a Hogwarts - wide competition and have to overcome the biases of their fellow students.
One popular 'Hufflepuff reader x Slytherin' fanfic is 'Green and Yellow'. It beautifully portrays the relationship between a Hufflepuff reader and a Slytherin character. The story shows how their different house traits create interesting dynamics as they navigate through Hogwarts together.
In a particular fanfic, a Hufflepuff character has a valuable magical item that some evil forces want to steal. The Slytherin main character, despite the typical house rivalries, decides to protect the Hufflepuff. This could be because they see the Hufflepuff's kind - heartedness and realize that the item in their possession is important for the good of the wizarding world. So, the Slytherin uses their intelligence and strategic thinking to keep the Hufflepuff and the item safe from harm.
One common theme is loyalty. Since Hufflepuffs are known for their loyalty, many fanfics will have the Hufflepuff OC being extremely loyal to their friends, standing by them through thick and thin. For example, in a lot of stories, the Hufflepuff character will defend their friends from bullies or support them during difficult times like exams or family issues.
Often, the story starts with Harry being sorted into Slytherin, which is a shock to everyone. Then the abuse begins, it could be from older Slytherin students or even some of the professors who have biases. As the story progresses, Harry has to learn to use his wits, which is a Slytherin trait, to fight back against the abuse. He might also have to deal with his own internal struggle of feeling like he doesn't belong in this house but still trying to make the best of it.