She might face some magical backlash. Saving someone from the veil could be against the natural laws of magic in the fanfiction world, so she could experience some physical or mental exhaustion as a result.
In the fanfiction, the Ministry of Magic could get involved. Since the veil is a mysterious and dangerous object, they might view Hermione's actions as interfering with something they don't fully understand. This could lead to her being investigated or even facing some form of punishment. On the other hand, among her friends and the Order of the Phoenix, she would be a hero. Her actions could inspire others to study more about the veil and its secrets, which could also put her in a position of being a sort of expert on the matter.
One consequence could be that Bellatrix becomes enraged and sets out to hunt Fred down. This would put Fred in constant danger as Bellatrix is a very powerful and vengeful witch.
She might face suspicion from her friends. Since Thorfinn Rowle could be associated with the dark side, her friends might not understand why she saved him. They could question her judgment and worry that she was getting involved in something dangerous or morally ambiguous.
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.
In some versions, Hermione might use her advanced magic knowledge. She could have discovered a spell that counteracts the pull of the veil. Maybe she found a way to disrupt the dark magic associated with it and was able to pull Sirius back from the brink just in time.
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.
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.
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.
He might face retaliation from Kikyo. Since Kikyo was intent on killing Kagome, Toga's interference would surely make her angry, and she could try to harm Toga in return.
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 Artemis becomes indebted to Percy. This might lead to her providing him with special favors or assistance in his future adventures. For example, she could offer her hunters to help Percy in a battle.