Well, they could have a very complex relationship. On one hand, they might be extremely competitive, always trying to outdo each other in everything from academics to impressing their parents. Since they are in Slytherin, they could also team up and be a formidable duo, using their combined wits to get what they want in the wizarding world. Maybe they have a secret pact to protect each other no matter what.
The twin could change a lot. He might be the one who stops Draco from making some really bad decisions. For instance, if Draco was about to follow Voldemort's orders blindly, the twin could convince him otherwise. This would then change the whole course of Draco's actions and how he interacts with Harry Potter and his friends.
He could be resentful at first. After all, his parents have kept this big secret from him his whole life. But as he gets to know his twin, he might develop a sense of brotherly love. He may also start to question his family's values and actions in hiding his brother, which could lead to a change in his own character.
One plot idea could be that Draco's twin sister is secretly a supporter of the Order of the Phoenix. She could be working undercover within the Slytherin house to pass information to the good side. Another idea is that she has a special magical ability that Draco doesn't, like the power to communicate with magical creatures in a unique way. This could lead to adventures where she uses this ability to solve problems or help her friends. Also, she might have a love story with a Gryffindor, which would cause a lot of tension between her and her family.
Self - discovery is also very common. Growing up as a Malfoy in the shadow of her brother, the sister often has to figure out who she really is. Is she just a Malfoy by name or does she have her own unique magic and personality? Fanfictions explore this by showing her journey, like learning new spells on her own or having a different view on the wizarding war than her family.
At first, she may avoid Harry Potter altogether. However, if she discovers something that links her family's past to Harry in a way that she didn't expect, it could draw her closer to him. For example, if there was a hidden connection between the Malfoy family and Harry's parents. As she delves deeper into this connection, she might start to protect Harry from other Slytherins or even from her own brother at times. Their relationship could be one of mutual discovery and slowly - growing trust as they face the threats in the wizarding world together.
Often, he is used to create more complex family relationships. He might be caught between Draco's actions and his own beliefs. He could try to redeem the family name in some fanfictions, which adds a new layer to the Malfoy story. He may also be in a love triangle or have some other romantic entanglements that further complicate his character and the overall plot.
One popular Draco Malfoy twin sister fanfiction is 'The Malfoy Heir'. It delves into the unique relationship between Draco and his sister in the wizarding world. The story often shows how she navigates Hogwarts life, dealing with the Slytherin house politics and her own identity within the Malfoy family.
Well, in some fanfictions about Draco Malfoy's little brother, he could be a bit of a rebel. He might not want to follow in the traditional Malfoy footsteps. He could be interested in Muggle things, which would be a huge shock to his family. This would lead to some really exciting plotlines where he has to hide his interests and navigate his family's expectations.