One interesting 'protega harry potter fanfic' could be the ones where the protagonist is a new student at Hogwarts who has a unique power to protect the school from a new dark threat. For example, a story where the character can control time to prevent Voldemort's return in a different way than in the original series.
It could be a Muggle - born protega. This character would face unique challenges as they try to protect the wizarding world while also dealing with their own identity issues. They might have friends among the Hogwarts students, and together they form a group to counter a new evil force that targets both Muggles and wizards.
In a Harry Potter fanfic, the protega spell could be used to protect a character associated with the lion (which might symbolize Gryffindor). The shield could be a physical or magical object that is enhanced by the protega spell. For example, a Gryffindor character might use the protega spell on their shield to defend against dark magic attacks.
The protega spell can be used to protect the shield. If the shield has a lion emblem on it, perhaps representing Gryffindor, the protega spell would strengthen the shield's defensive capabilities. It could prevent the shield from being damaged by dark magic or physical attacks.
There are 'Harry Potter fanfic fanfic' that focus on time - travel scenarios. Imagine if a character from the later books travels back in time to the first year at Hogwarts. This can create a lot of interesting plot twists as they try to change or preserve the original story line. Also, some fanfic fanfic might center around magical creatures in a way that wasn't fully explored in the original books, like the life of a hippogriff in more detail.
Some 'Harry Potter and Lily Potter fanfic' might focus on alternate universes. In one such story, Lily could have survived Voldemort's attack. She would then have to raise Harry in a world that is still recovering from the Dark Lord's first rise. This would change a lot of the dynamics in the story. Harry would grow up with his mother's love and protection, and Lily would have to deal with the knowledge that Voldemort could return at any time.
I'm not really in favor of the 'slaves' concept in fanfic as it can be a bit disturbing and against the positive spirit of the original 'Harry Potter' series. However, some fanfics might explore power dynamics in a more metaphorical way. But overall, the official 'Harry Potter' works focus on friendship, courage and magic, not slavery themes.
One interesting 'Harry Potter breed fanfic' story could be about the breeding of Hippogriffs in a more domesticated setting. Maybe it explores how wizards are trying to train them for various tasks like mail delivery in a different way than using owls.
One interesting 'Harry Potter Siren Fanfic' could be about a siren who uses her charm to influence the events at Hogwarts in a subtle way. Maybe she befriends Harry and tries to guide him through some challenges using her siren - like powers, which are different from magic but still effective.
There might be a fanfic where a MACUSA auror teams up with a Hogwarts student. They could be working together to stop a dark wizard who is causing chaos in both the American and British wizarding worlds. The story could explore how their different magical educations and approaches to magic come into play.
One interesting 'Harry Potter glutton fanfic' could be about Harry discovering a magical kitchen that creates endless amounts of his favorite wizarding treats. He goes on a bit of a food - filled adventure, trying all sorts of new and old magical delicacies.