One common theme is the 'opposites attract' scenario. For example, Reid, with his intellectual and often reserved nature, might be paired with a more outgoing and spontaneous character. Another theme is 'overcoming trauma together'. Given the dark nature of the Criminal Minds world, both Reid and his love interest might have to deal with the emotional scars from cases, and their relationship helps them heal.
A very popular theme is the 'slow - burn' romance. Since Reid is a complex character, his relationships often develop gradually over time. There's also the theme of 'intellectual connection'. His love interests usually share his love for knowledge or are intrigued by his vast intelligence. Sometimes, there are themes related to Reid's family issues, like how his relationship is affected by his mother's condition or his own past experiences growing up without a father.
Well, many fanfics focus on Reid's fight against the stigma associated with schizophrenia. He is a brilliant agent, and the idea that his mind could be 'broken' in this way is something he has to deal with. Also, his attempts to manage his symptoms while still being able to contribute to the BAU's cases are often explored in great detail. For instance, how he copes with the stress of a case when his schizophrenia might be flaring up.
Spencer Reid, the brilliant mind in Criminal Minds, could meet a forensic scientist in the story. They start off as colleagues, sharing their insights on cases. Slowly, Reid finds himself drawn to her intelligence and kindness. One day, after a particularly tough case, he finally musters the courage to ask her out for coffee. Their relationship blossoms as they discuss books, their shared love for knowledge, and of course, the intricacies of criminal profiling.
One common plot element is Reid using his vast knowledge to try and escape. He might analyze the behavior of his kidnapper, looking for patterns or weaknesses. Another is the emotional turmoil of the BAU team, especially his close friends like Garcia and Morgan.
A great love plot could be Reid falling in love with a victim - turned - advocate. After they meet during a case where she was a victim, Reid is impressed by her strength and determination to turn her experience into something positive. They keep in touch, and Reid helps her with some research for her advocacy work. This shared interest and her admiration for Reid's intelligence lead to a romantic relationship.
One common theme is Reid's vulnerability. Fans often explore how his intelligence and unique personality can make him a target in different ways. For instance, in some fics, his prodigious memory might be used against him, leading to his emotional or physical hurt.
Another theme is Reid's own personal growth during the ordeal. He may face his fears, or learn something new about himself. For example, in some fanfictions, he discovers a new level of strength or resilience that he didn't know he had while being kidnapped.
One common plotline is Reid getting physically injured during a case. For example, he might be shot while trying to apprehend a suspect. This then leads to the other team members worrying about him and his recovery process.
One common theme is the team's reaction to Spencer being hurt. It often shows how they come together to support him, like Morgan being overly protective or JJ showing her motherly side. Another theme is Spencer's own internal struggle. He's such a complex character, so when he's hurt, it can be about how he deals with pain, both physically and mentally.
One common theme is the idea of finding someone who can understand Reid's complex mind. Since he is highly intelligent, the love interest often shares his love for knowledge or has a deep understanding of his work. Another theme is healing. Reid has a lot of past traumas, and in many fanfictions, the love story helps him to heal and open up more. Also, the theme of opposites attracting can be seen, like Reid falling for someone who has a completely different background or personality but still complements him.
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.