Well, perhaps the Weasley family takes in a new house - elf that was previously under the Imperio curse by an unknown wizard. As the family tries to rehabilitate the house - elf, they discover that the curse has left some lingering effects. The Weasley children, with their knowledge of magic from Hogwarts, try different spells and potions to fully free the house - elf. Meanwhile, they have to be on guard as the wizard who cast the Imperio curse may come looking for the house - elf.
One possible fanfiction could be about a house - elf being put under the Imperio curse and being forced to spy on the Weasley family. The house - elf might struggle with the moral implications of its actions while the Weasley family starts to notice strange things happening around them.
In some fanfictions, Ron is put under Imperio to steal a powerful magical artifact. This creates a huge conflict as Harry and Hermione try to figure out why Ron would do such a thing without realizing he's cursed.
The house elf might be very grateful. Harry is known for his kindness, so the elf could see this as a chance for a better life. It might immediately start serving Harry with great enthusiasm, believing that Harry will be a fair and good master.
One interesting fanfiction could be 'The Unintended Consequences'. In this story, the use of Imperio on Ron by an unexpected character leads to a series of events that completely change the dynamics within Hogwarts. It shows how Ron's character, which is usually so loyal and steadfast, is forced to act against his will, and how his friends slowly start to notice the changes.
There could be many possibilities. It might be an original character created specifically for the fanfiction. However, it could also be a well - known house - elf from the original series, like Dobby, who in the fanfiction somehow comes to be owned by Harry Potter in a different set of circumstances. Maybe Harry saves Dobby in a more complex way in this fanfiction and as a result, Dobby becomes his house - elf.
Well, perhaps the house - elf is constantly tidying up in really cool ways. It could be folding clothes by magic so that they are always perfectly creased, or it might arrange the books in Harry's library in a way that makes it easier for him to find the exact spell book he needs at any given time. And it could also have a special connection with the other magical creatures around the house, like communicating with the garden gnomes and getting them to stay in line without causing trouble.
Dobby is often very popular in fanfiction. Since he was already a rather unique and brave house - elf in the original series, in fanfiction he can be portrayed in even more heroic or complex ways, like leading a revolution among house - elves.
Well, often in these fanfictions, if a Weasley is under Imperio, it can lead to a lot of drama. Let's say Ron is under Imperio. It could create a rift between him and Harry. The other Weasleys would then be on a mission to break the curse. Fanfiction writers might explore how the Weasley family dynamics change under such a dark spell. They might also show how different Weasleys react to the situation. Some might be more impulsive in trying to rescue the cursed one, while others might be more cautious and methodical.
Dobby would be a very likely candidate. He was already a prominent house elf in the original series and had a strong connection with Harry Potter. His brave and rebellious nature would make for great stories in a fanfiction where Harry is involved as a house elf too. Maybe they could have more adventures together, this time with Harry sharing Dobby's experiences.