A great fanfic in this crossover genre is 'Date A Ninja'. In this story, the Date A Live characters are quite intrigued by Naruto's world. They learn about ninjutsu and how Naruto's world is full of hidden powers. Meanwhile, Naruto has to adapt to the rules of the Date A Live world regarding spirits. It's a story full of cultural clashes and interesting character interactions.
Another aspect that makes it appealing is the chance to see how characters from different backgrounds interact. The characters in Naruto are used to a certain type of combat and way of life. When they meet the characters from Date A Live, who have different goals and ways of dealing with threats, it can lead to some really interesting storylines. For instance, Shido from Date A Live might learn some new combat techniques from Naruto, and Naruto could learn about the emotional side of dealing with spirits from Shido. This cross - pollination of ideas and skills is really engaging for readers.
Yes, there are some. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'roxas x date a live' and you'll find various stories. Some might be more to your taste in terms of writing style, plot, or character development.
I've read a fanfic where the Keyblade wielders from Kingdom Hearts end up in the world of Date A Live. It's called 'Keyblades in the Spirit World'. It has some really cool fight scenes and interesting character interactions as they try to find a way back home while also dealing with the Spirits.
The storylines could be combined by having a character from Naruto end up in the Date A Live world by accident. For example, Naruto could be on a mission and get sucked into a strange portal that leads him to the Date A Live universe. There, he could start interacting with the Date A Live characters, and his presence would disrupt the normal order of things. The Date A Live characters would have to figure out what to do with this strange ninja, and Naruto would have to adapt to this new world with its own set of rules and threats.
In a Naruto x Date A Live fanfiction, a great crossover would be in terms of combat strategies. The Date A Live characters are used to dealing with spirits in their own ways, but Naruto characters bring in a whole new level of combat knowledge. The Date A Live crew could learn about teamwork from Naruto's team formations. Also, the different elemental jutsus from Naruto could be incorporated into the Date A Live world, like using fire jutsu to fight against a particularly powerful spirit.
Characterization is key. The fanfic should stay true to the personalities of the characters from both series. In a good fanfic, Yozora from Kingdom Hearts would retain his cool and mysterious nature when interacting with the Date A Live girls. Also, the plot should be engaging, perhaps involving a common threat that requires the combined efforts of both sets of characters to overcome.
One possible plot could be that Naruto and his friends are somehow transported to the world of Date A Live. Naruto, with his determination and never - give - up attitude, could team up with Shido to fight against the Spirits that are causing chaos. Maybe Naruto's jutsu can be used in unique ways to deal with the Spirit - related problems, like using his Shadow Clone Jutsu to distract the Spirits while Shido tries to seal them.
There's also 'Date A Live: Ninja Invasion'. This fanfic has a really cool concept where the ninjas from Naruto start to show up in the Date A Live world, causing chaos and also creating some unexpected alliances. It's full of action and some really fun character interactions.
You can expect a crossover of two different fictional universes. It might blend the elements of the Kingdom Hearts world where Roxas is from and the Date A Live world. There could be new storylines involving the characters from both, and perhaps some interesting power combinations or interactions.