A more light - hearted plot could be Rossi's daughter falling in love with one of the BAU team members. This would create a lot of awkward and funny situations as they try to keep it a secret from Rossi, who is very protective of his daughter.
Often, it's portrayed as complex. Rossi is a workaholic, so his daughter might feel neglected at times. In some fanfictions, she tries to get his attention by getting involved in cases in her own way. For example, she might start researching similar cases on her own and then present her findings to Rossi, which could either make him proud or worried about her safety.
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 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.
One great place to start looking for Criminal Minds OC Rossi sister fanfiction is Archive of Our Own (AO3). There are often well - written stories there. You can search using the tags like 'Criminal Minds', 'Rossi', and 'OC' to narrow down the results.
Well, Tumblr can also be a source for Criminal Minds Rossi OC fanfic. There are often fanfic writers who post their works there. You can search using relevant tags such as #CriminalMindsRossiOC. However, the quality might vary, so you need to skim through a bit to find the really good ones. They could range from stories about Rossi's past interactions with an OC to how an OC might fit into the BAU team dynamic with Rossi.
One plot could be about how Baby Reid's intelligence makes him an outcast among other babies. He doesn't fit in with the normal baby activities and instead is more interested in observing and analyzing his surroundings. His parents worry about his social development but soon realize that his unique way of seeing the world is a gift. They start to find ways to nurture his intellect while also ensuring he has some form of normal social interaction, which could be a really heartwarming and interesting story.
One possible plot could be that a deranged fan, feeling betrayed by the show's direction, kidnaps members of the Criminal Minds team. The kidnapper might demand that the show be brought back in its original format. Another plot could involve a criminal who uses the guise of a fanfiction scenario to target the team, perhaps because they believe the team has wronged them in some way. Maybe a group of obsessed fans accidentally kidnap the team while trying to get an autograph or exclusive access in a really over - the - top and illegal way.
Well, I don't really recommend adult fanfiction as it may contain inappropriate content. But if we focus on general fanfiction of Criminal Minds, there are often stories that explore the backstories of the characters in more depth. For example, some might focus on Reid's childhood and how it shaped his genius but socially awkward personality.
Well, you could write a fanfiction where the BAU team gets trapped in a virtual reality world created by a tech - savvy unsub. They have to solve puzzles and cases within this virtual world in order to escape. Or perhaps a story where a new agent joins the team who has a psychic ability that they keep hidden at first. But as the cases progress, this ability starts to surface and help the team in unexpected ways.
One of the most intriguing plots could be a serial killer case that spans across both universes. Maybe the killer uses the intelligence - gathering techniques from Criminal Minds and the deductive reasoning of Sherlock. For example, the killer leaves clues that can only be deciphered by someone with Sherlock's skills, but the motives are related to the psychological profiling done in Criminal Minds. This creates a really interesting dynamic where the characters from both shows have to work together to catch the killer.