Loved it

Why did you delete all your other Naruto Crossover stories, I really liked them

Quick idea, make him use Arc of Space (Like Kamui). Grimoire teaches its members Lost Magic. Also, I prefer Ultear myself. But its your choice. I liked this story, so hopefully the next one will be even better. Have a nice summer.

Naruto and Mira

Wendy there are not enough naruto Wendy pairings

I like this idea, i hope naruto rips the mob apart and he makes it slow and painful.

NarutoxMira

I would say have Wendy be the pairing. Frankly with the way you are going to go. I would suggest have a Vanitas type of personality and Suit(His suit is fucking awesome) but with Vanitas type of personality he will need someone to balance himself out. Because I believe this Naruto will not be like Uitear who wasn't evil, but decided she will do anything she wants, because she will reverse time anyways at one magic. Would say have him like a more evil Gajeel when he was in phantom. Anyways Naruto would need someone to help balance himself out and Uitear wouldn't work and Mira is just used too often with Erza as a pairing.

I wonder if even during the tenrou island arc if he can take fairy glitter. Because seriously cana is worthless as a character.

Okay, hold up, not only do you have like 5 chapters dedicated to updates for a reboot but the reboot sounds terrible, why? Naruto with an avengers personality, Axel's catch phrase, Vanitas shadow magic and other voice actors!, Naruto already has a catch phrase, special techniques that can be converted to magic and a voice actor. You stated yourself you didn't believe Naruto would be an OC with Naruto's name? hypocrite, what does he have that Naruto has? his looks, name and parents, he has no Kurama, no Rasengan, his magic is based on shadows and some sort of shadow flame. Nothing about this OC of yours screams Naruto in any way and don't get me started on how you're butchering Fairy Tails story with your crossover characters and other OC's, it might sound harsh but your story is not a Naruto story.

I think Ultear is a better option for pairing, because in addition to meeting Naru when he joins Grimoire Heart, she has a very contrasting personality with Naru, while the little blond is a person who cares about his comrades and for their promises, Ultear is a master of deception and manipulation, I think you could create a good plot around them both.

If you give him darkness magic that is similar to vanitas may I suggest spells that are inspired by Terra's shotlock that draws on the power of darkness as well as Ansem that heartless familiar thing that hung around him was a beast in a fight. You could call it Shadow Guardian and it essential acts similar to the Guardian from kingdom hearts. Also I say keep it as mira

Another plot hole, why did Naruto and Natsu run to Sai's location when NARUTO CAN FUCKING TELEPORT. And don't give me some terrible excuse like "he forgot" he has trained with his magic for several years.

You haven't given anyone a proper reason to be stronger than in canon, so I call bs at that. Naruto is shown to easily beat Josef someone Laxus would have a difficult time beating. Your power levels are all over the place.

The shadow stone should be limited to only being able to summon dark copies of people that are weaker than yourself, even so it's broken, stupidly overpowered. You should've just not done the whole shadow stone thing.

I recommend staying with Mira. I feel Wendy is a bit too innocent a character to really relate to the whole "vengeance" angle you're going for. If your goal is to start dark and be redeemed, with someone getting through to him, it would be better to have someone like Mira who understands being in a dark place and holding anger. Being able to understand someone is necessary for getting through to them.

This is going on the assumption that it isn't going to be a villain story, but you mentioned joining Fairy Tail so I figured that was a safe assumption.

Ultear's obsession with going back into the past wouldn't really fit the vengeance angle either. Her whole thing is "nothing done will matter because it'll be different the second time around," after all. Not to mention she doesn't open her eyes until much later, so she wouldn't be much help in getting Naruto to move on.

These are just my thoughts based on what you've said of the story so far, though