Oz Vessalius is one of the main characters. He is a young nobleman with a mysterious past. Then there's Alice, a powerful being. And Gilbert, who is loyal to Oz.
Oz Vessalius is a great character to feature. His complex backstory, including his connection to the Abyss, gives a lot of room for exploration in a fanfic. Another good one is Alice. Her brash and often unpredictable nature can add a lot of interesting twists to a story. Also, Gilbert is a character full of loyalty and internal conflict, which can be used to create engaging storylines.
Since I haven't read the Pandora Hearts Cacus Race Novel, I can't say for sure. However, in the Pandora Hearts series, there are characters like Alice who is quite significant. In this novel about the Cacus Race, there could be characters directly related to that race who play the main roles, perhaps a Cacus Race leader or a young Cacus who has some special destiny within the story.
The main characters are Break and Alice. Break is a complex character with a mysterious past and unique abilities in the Pandora Hearts universe. He is often seen as a bit of an enigma.
A fanfiction could explore a scenario where the Sharingan in Naruto has a connection to the power of the Pandora Hearts world. Maybe Sasuke discovers that his Sharingan has a hidden ability that is related to the power of the Chains. This could lead to a whole new arc in his character development as he tries to understand this strange connection.
To develop your Pandora Hearts OC characters, start with their appearance. Their looks can say a lot about their personality. If they have long, flowing robes, they might be more mysterious or formal. Then, consider their skills and abilities. Are they good at sword - fighting? Or are they more of a strategist? Next, explore their fears and weaknesses. Maybe your OC is afraid of the Abyss because of a past trauma. By fleshing out these aspects, your OC will become more three - dimensional.