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 idea could be that the BAU team has to deal with a serial killer who is using ancient psychological torture methods. They have to quickly understand the killer's motives which are deeply rooted in some long - forgotten cultural practices.
One idea could be a vampire using their powers to manipulate crime scenes in ways that baffle the Criminal Minds team. For example, they could use their super speed to move evidence or their mind - control abilities on witnesses. Another plot could involve a vampire who is a serial killer, preying on victims in a pattern that the team has to figure out. Maybe the vampire has a moral code that only certain types of people are their targets, and the team has to understand this code to catch them.
A plot could involve Garcia's pregnancy being part of a dangerous case. The unsub could target her because of her pregnancy, seeing it as a way to get to the BAU. This would put her and her unborn child in great danger, and the team would have to go all out to protect her. Meanwhile, Garcia could also be dealing with her own fears and insecurities about becoming a mother in such a dangerous world.
One interesting plot idea could be a serial killer who targets both the FBI agents from Criminal Minds and the SWAT team members. The two teams have to combine their skills, with the Criminal Minds team analyzing the killer's psyche and the SWAT team providing on - ground protection and tactical support. For example, the killer might be leaving cryptic messages that only the profilers can decipher, while the SWAT team has to deal with the physical threats the killer poses during their investigations.
One idea could be that the Scorpion team is called in to help the Criminal Minds team with a case involving a highly intelligent criminal who is using complex technology to carry out their crimes. For example, the Scorpion team could use their skills to decrypt the criminal's encrypted messages that the Criminal Minds team couldn't crack on their own.
One idea could be that the BAU team from Criminal Minds is called in to investigate a series of murders that seem to have a connection to Dexter's 'hobby'. Dexter, being the secret serial killer who targets other killers, might initially be a suspect. Then, as the story unfolds, they could end up working together to take down a bigger network of criminals that neither could handle alone.
A great plot could be that the OC is a hacker who gets involved with the BAU because they unknowingly hacked into some information related to a serial killer. Morgan is assigned to keep an eye on the OC. As they work together, they start to respect each other's abilities. The OC could also have a personal vendetta against the killer which adds an extra layer of drama. They could also develop a romantic relationship as they solve the case.
Well, a cool plot might be that Sherlock and Reid from Criminal Minds get into a battle of wits over a case. The case could involve a super - intelligent criminal who is playing mind games with both of them. Or perhaps there's a case where the BAU's profiling skills are needed to understand the motives of a criminal that Sherlock has been chasing, but can't quite figure out the 'why' behind the crimes. And they end up learning from each other's methods.
A crossover with 'Sherlock' would be cool. Imagine Sherlock's deductive reasoning combined with the BAU's psychological profiling. They could be working on a case that involves a criminal mastermind who is playing mind games with both teams. Sherlock might initially be dismissive of the BAU's methods but then come to respect them as the case progresses.
Well, here's a plot. A new agent joins the BAU who seems to have a romantic interest in Reid. JJ gets jealous and starts to analyze her own feelings for Reid. Meanwhile, they are working on a case that involves a cult that has some sort of mind - control element. As they work to free the victims, JJ and Reid have to face their feelings head - on. This plot would involve a lot of drama, both in terms of the case and their relationship.