Harry might face backlash from the Death Eaters or Lucius' allies. They could see his actions as interfering in their affairs and target him more aggressively. However, on the other hand, it could also earn him respect from some within the wizarding community who see his act as a heroic and selfless one. It might also change the way the Hogwarts faculty views Harry, perhaps seeing him as more mature and responsible for taking such a risk to save a former rival.
One consequence could be that he gains an unexpected ally in Draco. Draco might feel indebted to Harry and start to change his views towards him, which could lead to some interesting interactions between them in the future. This could also cause some tension among their respective groups of friends.
For Harry, his friends in Gryffindor could be a bit confused at first. They know Draco is not exactly a friendly character. But overall, it could lead to a more united front against real threats in Hogwarts. The teachers might also take notice. Dumbledore, for instance, would probably be proud of Harry for showing such selfless courage, regardless of who he was saving.
Some fanfictions might depict that the wizarding community might see her as a hero. However, others could show that she faces backlash from some conservative wizards who think she overstepped her bounds. They might try to isolate her at Hogwarts or spread rumors about her. But her friends like Harry, Ron and Hermione would surely support her through it all.
He might face opposition from his own pure - blood community. Since Hermione is a Muggle - born, saving her could be seen as going against their traditional values. So he could be ostracized or face threats from some of the more extreme pure - blood families.
The wizarding world would be in shock. The Malfoys are known for their dislike of the Potters, so Draco saving Harry would go against the family's reputation. It could lead to Draco being ostracized by some in the pure - blood community.
She could face isolation within the Hogwarts community. The students might gossip about her newfound relationship with Lucius. Hermione may also become more involved in the darker aspects of the wizarding world if Lucius leads her that way. Her academic focus could shift as she gets caught up in the drama of this new relationship. Moreover, she may end up regretting leaving Draco if she later realizes that Lucius was just using her, and this could lead to a lot of emotional turmoil for her.
He could be doing it out of a sense of justice. Despite his family's views, Draco might see that the way the Dursleys treat Harry is wrong and decides to step in.
One consequence could be that it creates a rift between Ron and Hermione. Hermione might be grateful to Lucius, which could make Ron jealous or angry. This could lead to a strain in their relationship, and they might have to work through their feelings about Lucius' interference.
One consequence could be that Hermione becomes isolated from her original friends. Since she only trusts Lucius and Draco, her Gryffindor friends might not understand her actions and distance themselves from her.
In this scenario, it could also lead to a major shift in the relationships within the fanfiction. Hermione might feel betrayed if Draco doesn't stand up to his father. And Draco could be forced to make a difficult choice between his family's expectations and his feelings for Hermione. Lucius's interference could also bring in other elements of the wizarding world, like the Ministry or other pure - blood families getting involved depending on how the situation unfolds.
One consequence could be a change in the public's perception of Hermione. Some might see her as a hero for standing up against an unjust imprisonment, while others might view her actions as traitorous, especially if they believe Draco was truly guilty. This could create a divide among the wizarding community.