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.
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.
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.
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.
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 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.
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.
One example could be 'Batman and Terry: The Protective Bond' where Batman constantly saves Terry from dangerous situations and also mentors him to become a better hero. Another might be 'Protecting Terry: Batman's New Mission' which focuses on Batman's sole mission of keeping Terry safe in a Gotham filled with new threats.
One great example is 'The Protector's Pledge'. In this fanfiction, Draco finds himself drawn to protect Hermione from the dark forces at Hogwarts. It shows how their relationship evolves from animosity to a deep bond. Another is 'Shielding Hermione' where Draco defies his family's expectations to keep Hermione safe during a dangerous time in the wizarding world.
One example could be in a fanfiction where there is a new dark wizard threat at Hogwarts. Harry always makes sure Hermione is with him or in a safe place when they suspect danger. He might stand in front of her when the dark wizard's minions approach. Another example is when Hermione is researching a dangerous spell. Harry tries to limit her exposure to it, worried that it could backfire on her.