One example could be a fanfiction where Hermione is in a dangerous situation in the Forbidden Forest. Sirius, being protective, immediately apparates there to save her from a group of dark creatures. He uses his advanced magic skills to fend them off and then takes Hermione back to safety at Hogwarts.
There are fanfictions where Hermione is involved in a time - travel adventure gone wrong. Sirius, who has a connection to her through his friendship with Harry, senses her distress. He uses his knowledge of ancient magic (which he may have picked up during his time as a member of the Order of the Phoenix) to track her across time and space. Once he finds her, he does everything he can to get her back to the right time and keep her safe from the various threats she encounters during the time - travel chaos.
One example could be in a story where Hermione is in danger during a wizarding battle. Charlie, being protective, might swoop in on his dragon and shield her from the incoming spells. He could then take her to a safe location, away from the chaos of the battle, while constantly keeping an eye out for any potential threats.
I'm not sure of specific fanfictions where Hermione is depicted as a thief off the top of my head. But in some fanfiction, this might be part of a plot where she steals a powerful magical artifact to keep it out of the wrong hands, perhaps believing the Ministry or some dark forces are misusing or will misuse it.
There are fanfictions where a Slytherin forms a study group with Hermione. And when other students try to disrupt her studies or cause her trouble, the Slytherin stands up for her. Also, in some stories, a Slytherin who has a secret crush on Hermione will protect her from any sort of harm, whether it's from a jealous rival or a dangerous magical creature that gets loose on the school grounds.
In many fanfictions, Sirius Black might protect Hermione from various threats. For example, he could shield her from dark wizards who target her for her intelligence or her connection to Harry. He might also protect her from the more traditional Hogwarts bullies. His protective nature could stem from seeing her as a valuable member of the group around Harry, like a little sister figure.
One example could be if in the fanfiction Hermione suddenly hates books and knowledge. In the original, her love for learning is a core part of her character. So that would make it seem like she's not really Hermione.
In the wizarding world, there are always threats lurking. Hermione, with her inquisitive nature, sometimes gets into situations where she might be in over her head. Sirius, having a wealth of magical knowledge and experience, is seen as a perfect character to be her protector. Fanfiction writers like to play with this idea, showing how he can use his skills and instincts to keep Hermione out of trouble and safe from harm. It also adds an interesting layer to the relationships within the Harry Potter universe.
In some fanfictions, Hermione might have the power of omniscience. She could know everything that's going on in the wizarding world and beyond, just like a goddess of knowledge. For example, she can predict the future accurately and understand the deepest secrets of magic spells without much study.
Imagine a situation in fanfiction where there is a powerful magical artifact that is attracting unwanted attention. Hermione, being one of the few who can understand its significance and power, is in danger. Sirius Black, who has a sense of loyalty to those he cares about, would become her bodyguard of sorts. He would stay by her side, use his magic to create protective barriers, and fend off any who try to harm Hermione or take the artifact from her. He might also teach her some defensive magic techniques that are not taught in the regular Hogwarts curriculum to better equip her for such dangerous situations.
In some cases, Percy might be protective in more emotional ways. If someone were to say something mean or critical about Annabeth in the fanfiction, Percy would be quick to defend her. He would stand up for her and not let anyone undermine her confidence or abilities.
One great example could be a fanfic where Hermione discovers she has a connection to Sirius through some long - lost family magic. It might explore how they navigate their newfound sibling relationship while dealing with the wizarding world's challenges. For instance, they could team up to solve a mystery that involves both their pasts.