Obviously, Ichigo and Dark Ichigo are the central characters. Ichigo, with his complex personality and powers, is always a key figure. Dark Ichigo, being his inner Hollow, brings a lot of drama and conflict. The OC also becomes popular depending on how well - written they are. If the OC has unique powers or a really interesting backstory, they can gain a following among fans of the fanfiction.
Another concept could be the origin story of Dark Ichigo within the fanfiction world. It might be different from the original manga or anime, like Dark Ichigo being a result of an ancient curse that the OC is somehow involved in. This could lead to a whole new plotline where Ichigo has to not only deal with his inner Hollow but also the mystery behind it.
One common theme is friendship. Often, the oc forms a deep friendship with Ichigo, supporting him in his battles. Another theme is power discovery. The oc might discover new powers while being around Ichigo. For example, in some fanfictions, the oc's latent powers are awakened through Ichigo's influence.
Another one is 'A New Beginning'. Here, the OC is from a different dimension and accidentally ends up in Ichigo's world. Their encounter sets off a chain of events that leads to a deep and meaningful relationship. It explores themes of friendship, love, and sacrifice as they navigate the dangerous world of Hollows and Soul Reapers.
I'd suggest 'Unlikely Allies: Ichigo and the OC'. This fanfiction creates a really interesting dynamic between Ichigo and the original character. The oc has different beliefs and powers which clash and then blend with Ichigo's. There are also great character development moments for both. Additionally, 'When Ichigo Meets the OC' is a fanfic that focuses on the initial encounter between them and how that encounter sets off a chain of events that shapes their relationship in unexpected ways.
A great backstory is key. If the author can create a backstory that not only makes sense within the context of Bleach but also gives the OC depth and motivation, it will make the fanfiction more engaging. It could be something like the OC was created from a long - forgotten Hollow experiment in Soul Society.
First, know the characters well. Ichigo is a complex character with a strong sense of justice. Your OC should have unique traits that can complement or contrast with his. For example, if Ichigo is impulsive, your OC could be more level - headed. Then, create an interesting plot. It could start with an unexpected meeting between them, like the OC saving Ichigo in a battle. Use vivid descriptions to bring the story to life, especially during fight scenes or emotional moments.
One great Hollow Ichigo OC fanfiction is 'The Hollow Within'. It delves deep into the relationship between the main character's original self and the Hollow Ichigo aspect. The OC in this story has unique powers that are slowly revealed as the plot progresses, adding an interesting layer to the Bleach universe.
One idea could be that the OC has a special power that only activates when in close proximity to Ichigo. For example, the OC can sense Hollows from a great distance, which helps Ichigo in his battles against them.
One common theme is the discovery of self - worth. The OC often starts out feeling like an outcast but through their relationship with Ichigo, they come to realize their value. Another theme is the power of friendship. They support each other in battles and in dealing with personal issues.