Well, one idea could be exploring how a criminal family within the Naruto universe might have unique jutsu or abilities that are used for illegal activities. For example, they could have a jutsu that allows them to steal chakra undetected.
It could be the head of the criminal family, a powerful and cunning figure. Maybe someone who has a deep - seated grudge against the Hidden Villages and is leading his family in a vendetta.
One idea could be that Sakura's sister is a criminal because she was brainwashed by a powerful enemy. She might be forced to carry out heinous acts against the Hidden Leaf Village. The fanfiction could then focus on Naruto and Sakura trying to rescue her and break the brainwashing.
In some Naruto criminal fanfiction, a character could be framed for a crime they didn't commit. Let's say Naruto is framed for stealing a powerful weapon from the Hidden Leaf. He then has to prove his innocence while also finding the real culprit who is behind this elaborate scheme to create unrest in the village.
In a Naruto - based fanfiction, the female swordsman criminal could be a former member of a rogue ninja group. She decides to turn over a new leaf after realizing the error of her ways. However, the shinobi world doesn't trust her easily. She uses her swordsmanship not only to defend herself but also to prove that she can be a force for good. For example, she might start by helping villagers who are being attacked by bandits, gradually earning their trust and respect.
The character interactions are very unique. Naruto's exuberant personality next to the more reserved and serious Criminal Minds characters like Hotchner or Reid. It's like a clash of two different worlds. And then there are the ways in which the fanfiction might incorporate Naruto's jutsu, such as the Rasengan, into solving crimes or understanding criminal behavior. It's not something you see in the original shows separately.
Shikamaru could also be an ally. His intelligence would be invaluable in planning strategies and outwitting the more cunning criminals. He could help Naruto figure out the complex power structures within the underworld and come up with plans to either take them down or use them to Naruto's advantage.
Create an engaging plot. Maybe start with a mysterious crime that shakes the ninja world. For instance, a series of assassinations of important ninja leaders. Then, introduce your characters and their motives. If Naruto is the main character, show how he reacts to this new threat. You can also add some twists, like the criminal being someone close to Naruto or having a hidden agenda that no one suspects.
A Naruto Criminal Minds crossover fanfiction might involve the Criminal Minds team getting teleported to the Naruto universe. They would be shocked by the different world with chakra and ninjas. The ninjas, on the other hand, would be curious about the strangers' strange methods of solving problems. The story could revolve around a series of murders in a ninja village that seem to have no pattern. The Criminal Minds team then uses their knowledge of human behavior and profiling while the Naruto characters use their ninja skills to catch the culprit together.
The theme of redemption can also be found. Just as some characters in Naruto seek redemption for their past actions, in the context of Criminal Minds investigations, the idea of criminals seeking redemption or the characters in the Criminal Minds team dealing with their own past traumas while trying to bring about justice can be explored. It adds an extra layer of depth to the crossovers.