Perhaps an interesting plot point is how other characters in the wizarding world react to Harry owning Dobby. Some might be jealous that Harry has such a loyal and resourceful helper, while others could be concerned about the implications of a wizard 'owning' a house - elf in a more official capacity.
One interesting plot point could be how Harry's ownership of Dobby changes their relationship dynamic. Maybe Dobby becomes even more protective of Harry, going to extreme lengths to keep him safe. For example, he might use his unique house - elf magic in new and creative ways to defend Harry from dark forces.
The exploration of Dobby's relationship with Harry beyond what's in the books is really interesting. In fanfiction, we might see Dobby being more of a confidant to Harry, and their conversations can be really deep. Like in one story, Dobby gives Harry advice on how to deal with his feelings about Voldemort that no one else could give. This kind of emotional connection is a great plot addition.
His loyalty to Harry could intensify. Knowing that Harry is his owner in this fanfiction, Dobby would likely double down on his efforts to protect Harry. This could lead to him making sacrifices he wouldn't have considered before. He might even put himself in more dangerous situations to ensure Harry's safety.
One interesting theme is Dobby's search for freedom and identity. Since he was a house - elf, his journey to become more than just a servant is a great theme. Another could be his friendship with Harry Potter and how it evolves over time.
In some fanfictions, Dobby might form an unlikely friendship with other Hogwarts students. He could teach them about house - elf magic, which is something not really covered in the original books. For instance, Dobby could show them how to use his brand of household magic for protection spells around the school during the dangerous times when Death Eaters are on the prowl.
One possible plot development could be that Dobby uses his unique house - elf magic to help Harry in ways that are unexpected. For example, Dobby might be able to access hidden chambers or secrets within Hogwarts that even the teachers don't know about. This could lead Harry to discover new spells or artifacts that give him an edge against Voldemort.
Perhaps Harry and Dobby bond over a shared love for a particular kind of magic, like house - elf magic. Dobby could teach Harry some unique spells or magical tricks that only house - elves know, which is really exciting in the story.
One plot could be that Dobby has overheard some important conversations among the Death Eaters. Harry Potter, being the one who listens to Dobby, then uses this information to try and foil their plans. This could lead to a cat - and - mouse game between Harry and the Death Eaters. Along the way, Harry might learn more about the wizarding underworld and Dobby could prove to be an even more valuable ally than before, as they navigate through a web of lies and danger.
There could be a really interesting plot where the werebear nature of Harry Potter in the fanfiction is a closely guarded secret. He has to struggle with hiding this new aspect of himself while also dealing with his regular Hogwarts life. He might face challenges like accidental transformations during full moons and having to cover it up from his friends. And maybe the werebear side of him has a connection to an ancient prophecy in the wizarding world that only he can fulfill.
In some fanfictions, Dobby uses his unique magic skills to create elaborate pranks against Harry's enemies at Hogwarts, which adds a lot of humor to the story.
A great plot point might be Arwen's perspective on the concept of magic in the Harry Potter universe compared to that in Middle - earth. Since she has a different understanding of magic, her reactions and interactions with the wizards could be really fascinating. For instance, she might be surprised by some of the more 'brute - force' spells used in the wizarding world, while the wizards might be in awe of her more subtle and nature - based elven magic. Another interesting aspect could be if Arwen gets involved in the fight against Voldemort. Her elven wisdom and powers could potentially change the course of the battle in unexpected ways.