Hello, dear writers! I have thought out a fairly interesting challenge for you. The challenge will be a NarutoxFairytail crossover. Here is a short plot.
As the great strategist, Mavis Vermillion knew that one day Zeref will make his move. She knew about Kyuukimon and also knew about E.N.D. Therefore she left not just Lumen Histoire, but one more 'thing' as well. It was her child, well not from birth, but create by her Reality Illusion magic. A being with a code name N.U.L.L. Mavis expected for N.U.L.L to become a trump card and counter measure against Zeref's Etheriouses. N.U.L.L was created for one purpose to stop E.N.D.
One more thing, N.U.L.L's magic is Metsuaku mahou aka Demon Slayer magic. You can choose the element of his magic. N.U.L.L is also one of the two top secrets of Fairy Tail which only Master allowed to see.
About his personality. Well, that's up to you as well. He can either be like canon Naruto or be a silent genius or even has a habit of pissing off the other members of Fairy Tail with his comments each time when he saw they did something awkward, mainly Natsu.
Pairings is up to you. And for those who didn't understand, N.U.L.L is a full name of Naruto. You can either thought out of a way to decipher yourself or you can PM me because I've already some idea about the cipher of Naruto name. This will take place at the start or middle of Tartarus arc. Good luck with this challenge and if you agreed then write the answer as review.