One concept could be an OC who is a time - traveler and has to interact with Hirako Shinji at different points in his life. This would add an element of mystery and could change the course of the original story in unexpected ways.
Start with a distinct personality trait. For example, if you want your OC to be the opposite of Shinji in some ways, make them extremely confident and outgoing. This contrast will create interesting dynamics between the two characters.
One possible plotline could be that Shinji discovers a female character he cares about is pregnant, and he has to deal with the shock and then step up to support her. Maybe he has to face some challenges within his group or community because of the unexpected pregnancy.
There may not be a large number of Shinji Hirako fanfictions with a pregnancy plot specifically. However, if you join some Bleach - related fan communities (since Shinji Hirako is from Bleach), you might be able to ask fellow fans if they know of any such stories. They could point you in the right direction or even share some unpublished works they are aware of.
Many 'shinji x oc persona fanfiction' explore the theme of identity. The OC might be from a different background or have a unique personality, and the story delves into how they fit into the 'Persona' world. There's also the theme of redemption. If Shinji has some flaws or past mistakes, the relationship with the OC could be a path for him to redeem himself. And of course, the theme of growth is common. Both characters grow and develop as they interact with each other in the story.
Love and acceptance is also a prevalent theme. Given their complex personalities and difficult pasts, fanfics often center around how they come to love and accept each other. This might involve accepting each other's weaknesses as well as strengths, and learning to be there for one another in a more meaningful way.
Another theme might be the reaction of other characters. For example, how his friends or family in the Evangelion universe respond to his crossdressing. It could range from shock to acceptance, and this can create interesting storylines. Often, it can also be a way to explore relationships in a different light. Maybe a character who had a certain view of Shinji before sees him in a completely new way because of the crossdressing.
Another aspect is the re - imagining of the Evangelion world around their relationship. Writers might change certain events or add new ones to create a more conducive environment for their relationship to develop.
The relationship between Shinji and Misato in fanfic can take many forms. One common aspect is the contrast between their personalities. Shinji is often shy and introverted, while Misato is bold and outgoing. This contrast can create interesting situations where they influence each other. For example, Misato might encourage Shinji to be more confident, and in turn, Shinji's innocence could make Misato re - evaluate some of her own actions. Fanfic writers use this relationship to explore different emotional and psychological aspects within the Neon Genesis Evangelion universe.
Character development of Shinji is also a major element. In the fanfic, Shinji has to grow and change. He may start as the same timid character from Evangelion, but the challenges in Berserk force him to become stronger and more confident. This transformation is what makes many of these fanfics appealing.