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.
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.
One great piece of 'Supernatural' and 'Torchwood' crossover fanfiction is 'The Convergence'. It weaves together the two universes really well, with the characters from both shows interacting in a very believable way. The story has a great plot that involves a common threat that both the Winchester brothers from 'Supernatural' and the Torchwood team need to face. It's full of action and also some really interesting character moments.
One common theme is the clash of different kinds of supernatural or otherworldly elements. Since 'Supernatural' has a lot of demons, angels, and ghosts, and 'Torchwood' deals with aliens and time - space anomalies, when they cross over, there's often a struggle to understand and combat these different threats. For example, in many fanfics, the characters have to figure out how to fight an alien - possessed demon or something similar.
Character consistency is a key element. The characters from Torchwood should act in a way that is true to their original personalities. For example, Captain Jack Harkness should be flirty and fearless as he is in the show.
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.
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.
Well, Jack Harkness from Torchwood would probably be quite intrigued by Sherlock's deductive abilities. He might initially test Sherlock, throwing out strange cases to see how he solves them. Sherlock, on the other hand, would likely be a bit put off by Jack's flamboyant nature at first but would soon realize his value in dealing with the more otherworldly aspects of cases.
One interesting plot could be where the Torchwood team investigates a series of strange murders that seem to have a supernatural element, and they enlist Sherlock's help. Sherlock, with his deductive skills, starts to piece together clues that the Torchwood team might have overlooked. For example, he could notice a pattern in the victims' backgrounds that leads to a bigger conspiracy.