Yes, often there could be. For example, the story might explore how Harry and Draco's relationship changes when they are somehow related to the Riddle twins. It could involve them uncovering secrets about the Riddle family's past that impacts their own identities and destinies.
Maybe in this fanfiction, the fact that they are the Riddle Twins causes a stir in the wizarding community. Some people might fear them because of their connection to Voldemort, while others believe they could be the key to finally bringing true peace. Harry and Hermione then have to deal with the prejudice and the high expectations placed on them. They might have to prove that they are not like Voldemort and that their heritage can be used for good.
One interesting plotline could be that they discover their twin relationship early on and try to keep it a secret from everyone at Hogwarts. They might secretly help each other out in classes and with their rivalries against other houses.
A possible plot is that they are on a quest to find out more about their family history as the Riddle Twins. Along the way, they encounter various magical artifacts and spells that are related to the Riddle family. They might also have to deal with the Death Eaters who either want to recruit them or eliminate them. Harry could use his Gryffindor qualities to protect Draco at times, and Draco could use his Slytherin knowledge to help them outwit their enemies. This journey could lead to self - discovery for both of them and a new understanding of their place in the wizarding world.
Well, Harry and Draco are the key players. Harry with his Gryffindor friends and Draco with his Slytherin associates might all be involved in the story. The Riddle twins, though not as physically present perhaps, are important as they are the factor that ties Harry and Draco in this fanfiction. Their connection to the Riddle twins could bring in elements of the dark past of the wizarding world and how it affects the present situation of Harry and Draco.
One interesting plotline could be how they deal with the reactions of their friends. For example, Hermione might be very confused at first but then start to notice the small differences between them that no one else does. Another could be their family dynamics. How would the Malfoys and the Potters react to the discovery? It would surely cause a stir in both families.
Harry's personality could shift towards being more introspective. He would constantly be thinking about the implications of being a Riddle. His sense of justice might still be strong, but he could be more cautious in his actions. Draco might experience a major change. He might lose some of his arrogance as he realizes that being a Riddle doesn't automatically mean power and privilege. Instead, it comes with a lot of baggage. He could become more collaborative, working with Harry instead of against him, and might even show more kindness towards those he previously looked down upon.
Another interesting plotline could be that Draco and the Weasley Twins are all chosen for a special, dangerous mission. At first, they are reluctant to work together, but as they face various challenges, they start to rely on each other's strengths. The Twins' knowledge of charms and potions for practical jokes turns out to be useful in a combat - like situation, and Draco's knowledge of dark magic (from his family background) helps them understand and counter some of the threats they face. This forces them to re - evaluate their opinions of each other and form an unlikely bond.
In some fanfictions, their twin status might change the way the Sorting Hat sorts them. Instead of Harry going to Gryffindor, perhaps they both end up in Hufflepuff because of their shared values that are more in line with that house. This could lead to a completely different story arc where they are known for their loyalty and hard work rather than Harry's typical Gryffindor - like heroics. Also, their family relationships would be different. The Dursleys might have to deal with two magical children instead of one, which could change the way Harry (and Neville) grow up and view the Muggle world.
A possible plotline is their different magical abilities. Percy might be really good at transfiguration and charms, while Harry has his natural talent for defense against the dark arts. They could compete in a friendly way, but also learn from each other. For instance, Percy could teach Harry some advanced transfiguration spells, and Harry could show Percy some new defense techniques he learned from his experiences.
One interesting plotline could be the Carrow twins trying to manipulate Harry into joining their dark deeds, but Harry resists and tries to turn them to the good side. Another could be Harry forming an unexpected friendship with one of the twins that causes a rift between the twins themselves.