His courage becomes more evident. By saving Hermione, he shows that he is willing to face great danger for his friend. This act of heroism can make him more confident in his abilities as a wizard.
In this kind of fanfic, one possible scenario could be that Harry uses his quick thinking and magical skills. For example, he might use a stunning spell on the troll just in time to stop it from harming Hermione. Another scenario could be that Harry lures the troll away from Hermione, using his knowledge of the troll's behavior. Maybe he throws something noisy in the opposite direction to draw the troll's attention.
Well, in many such fanfictions, Harry might use his magic skills. He could cast a powerful stupefy spell on the troll to stop it in its tracks and then quickly lead Hermione to safety. Maybe he also uses his quick thinking and knowledge of the Hogwarts corridors to find a hiding place where the troll can't reach them.
Hermione could develop a more complex understanding of magic. Since saving Harry's parents would likely involve delving into some very rare and powerful magic, she would expand her knowledge greatly. This new knowledge could make her more respected among the wizarding community, and she might use her new status to advocate for better magical education and research, all while her character grows in wisdom and leadership.
One reason could be that the troll is simply on a rampage and Hermione was in the wrong place at the wrong time. Trolls are not known for their intelligence, and it might have just stumbled upon Hermione while wandering the Hogwarts halls.
Well, it could start with Hermione being in a vulnerable situation, like being cornered by the troll in a dark, damp dungeon. Harry, being the brave hero, arrives just in time. He might first distract the troll by conjuring up some annoying little creatures that the troll would start chasing. Then, when the troll's back is turned, Harry would grab Hermione and apparate them both to a safer place, like the Gryffindor common room.
Harry might develop more patience. Usually, he can be a bit impulsive, but when it comes to saving Hedwig, he has to be careful. He has to think through his actions before making a move. For example, if he's facing a powerful dark wizard who has Hedwig captive, he can't just rush in. He has to plan, and this planning helps him grow as a more patient person.
One possible plot twist could be that the troll is actually under the control of a dark wizard. So when Harry saves Hermione, they realize that there is a much bigger threat at hand. Another twist could be that the troll turns out to be a transformed Hogwarts student, and they have to find a way to reverse the spell instead of just fighting it.
Hermione's character could develop in terms of her relationships. Through saving Fred, she might form a stronger bond with the Weasley family. She may also become more empathetic as she experiences the fear of losing someone dear. She realizes that there are things more important than just academic knowledge. So, she starts to balance her intellectual side with her emotional side more effectively.
Well, he could use his magic skills. Maybe he casts a powerful spell on Ron to stop him and then takes Hermione to a safe place, like Hogwarts where there are protective enchantments.
Well, in many fanfics, Harry might use his quick thinking and swimming skills. He could have found Hermione using his magical connection to her or by following the signs in the underwater maze. Maybe he used a spell to break whatever was binding Hermione and then swam her back to the surface.