The theme of identity is quite prevalent as well. An Uchiha oc in a fanfic may question who they are, especially considering the unique nature of the Uchiha clan. Are they defined by their clan, by their powers, or by their own individual choices? This internal conflict is often explored in great detail, making for a very engaging read.
Power and redemption are common. Since the Uchiha are known for their powerful Sharingan, male OCs often strive to master this power or atone for misusing it. For example, an OC might have accidentally hurt a loved one with his Sharingan powers and then seek redemption.
One interesting Uchiha OC fanfic could be about an Uchiha OC who discovers a long - lost Sharingan technique. This OC might be an outcast in the clan due to their unique ideas about using the Sharingan. They then go on a journey to master this new technique and in the process, they make unexpected allies within the clan who start to see the value in their unorthodox ways.
When it comes to her personality, she could be a bit of a rebel. Since she has pyromaniac tendencies, she might be a bit impulsive when it comes to using fire - based jutsu. She could also be a loner, as other characters might be a bit wary of her because of her dangerous hobby. You should also consider how she interacts with other Uchiha clan members and how they view her.
Another option is to check out Naruto fanfic subreddits. There are a lot of fans who are into creating and sharing interesting fanfics. You can specifically ask for fanfics that feature a female Uchiha character with pyromaniac tendencies and see what comes up.
Maybe the fanfic could start with the OC being experimented on by Orochimaru. Naruto and Itachi somehow cross paths with the OC. Itachi, seeing the OC's situation, decides to help, which leads to a complex relationship between them all as Naruto tries to understand Itachi's motives and the OC tries to break free from Orochimaru's control.
Another aspect is their backstory. Maybe the Uchiha OC was raised outside the main clan for some reason, like their parents were exiled. This would give them a different perspective on the clan's traditions and values. They could bring in new ideas and ways of thinking when they return to the clan, which would make for an interesting story as they interact with the more traditional Uchiha members.
First, give the OC a strong backstory related to the Uchiha clan's history. Maybe they were a survivor of the massacre or had a family member who was wronged. Second, develop their unique abilities. It could be a special form of the Sharingan or a new jutsu. Third, define their personality. A brooding and determined personality would fit well, as they are on a revenge quest.
Well, 'A Uchiha's Redemption' is also a great 'naruto uchiha oc fanfic'. In this story, the original character, who is an Uchiha, has to face the dark past of the clan and strive for redemption. The author does a wonderful job of integrating the character into the existing Naruto lore, making it an exciting read. It delves deep into the Uchiha's emotions and the complex relationships within the clan.