One idea could be that a case starts in Hawaii and has connections to Los Angeles. The teams from both shows have to collaborate. Maybe a criminal organization is operating in both locations and they are smuggling some high - tech weapons. The characters from Hawaii Five 0 like Steve McGarrett could team up with the NCIS LA agents like G. Callen to take down the bad guys.
In a crossover fanfiction, you could focus on the relationships between the characters. Perhaps there could be a bit of friendly rivalry at first between the two teams. But as they work together, they start to respect each other more. For instance, some of the more serious - minded characters from NCIS LA might initially clash with the more easy - going ones from Hawaii 5 - 0. However, by the end of the story, they become good friends and allies, having learned from each other's ways of doing things.
Common themes in these crossovers include the sharing of resources and expertise. The teams in 'Hawaii Five O' and 'NCIS LA' have different skills and technologies at their disposal. In the fanfiction, they combine these to take on powerful enemies. There can also be themes of cultural clashes and integrations. The Hawaiian culture in 'Hawaii Five O' is quite distinct from the more urban culture in 'NCIS LA'. Writers might explore how the characters from different backgrounds interact with each other, whether it's through misunderstandings at first or a newfound appreciation for each other's ways of doing things.
One idea could be that the teams are brought together to solve a case involving a military - related crime that has ties to Hawaii. Maybe a stolen military weapon is being sold on the black market there. The characters from Hawaii Five - 0 can provide local knowledge and connections, while the NCIS agents bring their expertise in military investigations. Another idea is that a Navy officer goes missing in Hawaii and both teams have to work together to find him. They might initially have some clashes in their working styles but eventually learn from each other.
One idea could be that a case in Hawaii has connections to a national security threat that NCIS is already investigating. For example, a suspected terrorist cell in Hawaii might be linked to a larger international network that NCIS has been tracking. Agents from both teams could collaborate, with the Hawaii Five 0 team providing local knowledge and the NCIS agents bringing in their expertise on international threats and military - related matters.
Another challenge could be the difference in resources and technology. They might use different equipment and have different access to information. For example, NCIS LA might have more advanced forensic technology due to their connection with the Navy, while Hawaii Five 0 might have more local knowledge and informants. Combining these resources effectively could be a struggle for the characters in the crossover.
A possible plot could involve a missing person who has a connection to both Hawaii and LA's military. Hawaii Five - 0 starts the search in Hawaii and discovers that the person was last seen with some individuals who are under NCIS LA's surveillance. This leads to the two teams collaborating. They face many obstacles along the way, like interference from some powerful and shadowy organizations who don't want the person to be found.
One place to find such fanfiction could be Archive of Our Own (AO3). There are often many creative crossovers there. Just search for 'Hawaii Five O NCIS LA crossover' on the site and you'll likely discover a bunch of interesting stories written by fans who love both shows.
Kono Kalakaua would also be a great character to focus on. Her computer skills and her ability to handle herself in dangerous situations could be very useful in a crossover. Paired with Kensi Blye from NCIS LA, they could form a powerful female duo. They could share their experiences, compare their skills, and work together to solve the case.
A scenario could be a missing person case that spans both areas. The NCIS LA team starts the investigation on the mainland when they realize the person might have headed to Hawaii. Then they call in the Hawaii 5 - 0 team for help. As they search, they discover that the missing person is involved in some sort of international conspiracy that both teams have to unravel.