One common theme is family. Since the OC is a sister, there's often exploration of family dynamics within the context of the BAU. Another theme is acceptance. The OC sister usually has to prove herself to the team and gain their acceptance. For example, in many stories, she might have an unorthodox method of profiling that the team is initially skeptical about.
The theme of mystery and danger also runs through many of these fanfictions. The sister might get involved in the cases either by accident or because she has some special knowledge. This leads to her being in dangerous situations, much like the BAU team, and having to use her wits to get out of them.
A frequent theme in these fanfictions is the OC's hidden talents or abilities. For instance, she might have a special skill in profiling that she's been developing on her own. This theme of self - discovery within the context of the 'Criminal Minds' universe is really engaging. Also, the theme of friendship within the BAU is often explored as the OC sister forms relationships with the other members of the team like Reid or Morgan.
Family relationships are a very common theme. Since it's about Rossi's sister, exploring how they interact as family members, with all the love, conflicts, and support that comes with it. Another common theme is mystery. Given the Criminal Minds setting, the sister might be involved in some sort of mystery related to the BAU's cases.
A common theme is family dynamics. Since it's about Tara and her OC sister, exploring their relationship, whether it's a loving bond or a more complex, strained one, is often seen.
A frequent theme is the OC's integration into the BAU. Since it's an original character, the fanfic often focuses on how they fit into the team dynamic. They might face challenges from other team members or have to prove themselves. In relation to Rossi, the OC could also be involved in Rossi's personal life, like helping him deal with his past traumas or family issues. For example, in some fanfics, an OC might be a psychologist who helps Rossi come to terms with some of the darker aspects of his past cases.
In Criminal Minds Penelope x OC lemon fanfiction, a recurring theme is the discovery of new emotions. Penelope, being a well - established character, may experience different feelings when the OC enters her life. This can lead to themes of self - discovery for both characters. Additionally, there might be themes of secrecy and the challenges of keeping a relationship under wraps in a work - centered environment like the BAU. But again, due to the 'lemon' nature, there could be some more mature themes such as sexual exploration that are part of the relationship development in these stories.
Family bonds are a common theme. Since it's about Prentiss and her daughter, it often explores how they interact and support each other.
Many fanfics also focus on the OC being a source of support and stability for Reid. Given his troubled past and the often - disturbing cases he deals with, having someone to lean on is a big part of these stories. It's about how the OC helps Reid grow as a person and a profiler.
A prevalent theme is redemption. In Criminal Minds, some criminals may seek redemption or the team tries to understand if there's any chance of it. In supernatural fanfic, a character who has made mistakes in the past might try to make up for it. Also, the theme of sacrifice. The characters in both might have to sacrifice something for the greater good, whether it's their safety in Criminal Minds or their powers in a supernatural setting.
Another theme is the transformation of the characters. Sometimes, a character from Criminal Minds might be turned into a vampire or be influenced by vampire powers. This leads to internal conflicts within the character and also changes their relationships with the rest of the team.