Well, perhaps there's a Highlander who stumbles into the wizarding world. He might be confused at first by all the magic but then realizes he can use his immortality and combat skills to his advantage. He could get involved in the fight against Voldemort, using his unique abilities. Or, there could be a magical tournament in the Harry Potter world that also includes Immortals from the Highlander world, and they compete using both magic and their Highlander powers.
Hermione Granger would be a great choice too. Her thirst for knowledge would lead her to study the lore of the Highlanders intensively. She could figure out ways to use magic to either protect Immortals or find a way to end the immortality curse if she saw it as a danger. Her intelligence would make her a force to be reckoned with in the Highlander's world.
A character like Harry Potter himself might be initially skeptical of a Highlander. But when he sees the Highlander's combat skills and immortality, he could be intrigued. He might try to learn from the Highlander's fighting techniques to use against Voldemort. On the other hand, a Highlander could be amazed by the magic in the Harry Potter world, like seeing a simple levitation charm.
Maybe a story where Harry Potter himself is revealed to be an Immortal. He would have to balance his fight against Voldemort with the rules of the Highlander's world. This could add a whole new layer of complexity to his journey. He might learn new combat skills from the Highlander lore and use them against Death Eaters.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, including Highlander crossovers. Just use the search function and type in 'Highlander Crossover' to find relevant stories.
Yes, there are likely some interesting ones. You can start by looking on fanfiction websites. Some might explore unique character interactions, like how the characters from Torchwood would interact with the immortals in Highlander. They could create new and exciting storylines that combine the two universes' mythologies.
The uniqueness lies in the combination of two very different universes. NCIS is a modern - day crime - solving show, while Highlander has elements of immortality and a different kind of combat. When crossed over, it can create stories that are full of contrasts and new possibilities.
Yes, there are likely some interesting ones out there. A good place to start looking could be on fanfiction websites like Archive of Our Own. Some might explore how the characters from NCIS interact with those from Highlander in unique crime - solving scenarios or character - development arcs.
There could be a 'forever highlander crossover fanfiction' that pairs the Highlander with the 'Buffy the Vampire Slayer' world. Imagine a Highlander in Sunnydale, facing vampires and demons. His immortality would give him an edge in battles, and his code of honor might clash or align with Buffy's mission. It would be a great mix of two different supernatural concepts.
You can try websites like Archive of Our Own (AO3). It has a vast collection of fanfiction from various fandoms, and there's a good chance you'll find some torchwood highlander crossover stories there.