Well, one possible plot development could be that the Malfoys, in rescuing Harry, have a change of heart towards the whole fight against Voldemort. Maybe they start to see the error of their ways and side with Harry more openly. For example, they could use their influence in the wizarding world to help Harry gather more allies.
I think Dobby could also be a significant character in this fanfic. Since he has connections to both the Malfoys and Harry. He might be the one who gives the Malfoys the idea to rescue Harry or helps in the rescue in some way. Also, Voldemort or his Death Eaters could be important in the background as the threat that Harry needs to be rescued from. Their presence would constantly loom over the story, making the Malfoys' actions more dangerous and significant.
Obviously, Harry Potter is one of the main characters. He is the one who is being helped by the Malfoys. Then there are the Malfoys themselves. Lucius Malfoy, with his knowledge of the dark wizarding world and connections among the Death Eaters, could play a crucial role. Draco Malfoy is also important as his relationship with Harry has always been complex and in this fanfic, it might be a key factor in his family's decision to help Harry.
Harry could develop a more guarded personality. Since the Malfoys have a certain reputation, he may need to be careful about his actions and words. He might also become more calculating in his interactions, learning from the Malfoy family's political maneuvers.
Perhaps in the fanfic, the Malfoys help Harry because Draco has a change of heart after seeing the true brutality of Voldemort's regime. This could lead to the Malfoys providing Harry with a safe haven when he's on the run, which is a very interesting turn of events as they were once his enemies.
The Malfoys could save Harry in fanfiction because of a personal debt. Maybe Harry once unknowingly did something that benefited the Malfoys greatly. This could be as simple as preventing a disaster from befalling their family business or saving the life of a family member secretly. When the time comes, the Malfoys feel obliged to return the favor and save Harry from whatever danger he is in. Also, it could be part of a complex plot where the Malfoys are trying to redeem themselves, and saving Harry is a big step in that direction.
In Harry Potter fanfiction, the Malfoys are often portrayed in a more complex and sometimes positive light. Some fanfictions might explore Draco Malfoy's struggle between his family's beliefs and his own emerging sense of right and wrong. He could be shown as having a change of heart, perhaps influenced by his interactions with Harry and his friends. This gives a new dimension to his character that we don't fully see in the original books.
Well, if the Malfoys raised Harry, it would likely cause a lot of conflict and changes. Their pureblood ideology could clash with Harry's natural sense of justice and kindness. Also, the relationship dynamics within the Malfoy household would have a major impact on Harry's character development.
One interesting plot point could be how Harry adapts to the Malfoy family's pure - blood traditions. He might struggle with their values at first. For example, the Malfoys' view on blood purity and how that contrasts with Harry's more inclusive nature.
Well, it could go a few ways. One possibility is that the Malfoys would start their typical taunting of Harry. Lucius might look down on Harry with disdain and make some veiled threats. Narcissa, on the other hand, could be a bit more reserved. Harry, being Harry, would likely respond with his own brand of courage. He might even try to use the situation to gain some information about the Malfoys' recent activities if he suspected they were up to no good.