Darker Naruto in Gotham
Naruto in his late 20s early 30s has lost most of his loved ones after enemies he didn't kill came back and killed them.
So starts to actually kill his enemies.
He Dosent Care about being hokage anymore and spends all his time training.
Kakashi is killed and in his last breath makes naruto take his eye.
To honor kakashi he learnt the Chidori and even reads the books he was always reading.
(naruto way more powerful than canon and has a lot more variety in his jutsu, he even learns sealing and he can use a sword he is also above mighty guy level in hand to hand )
A ninja tries to take kurama out of him using a unknown forbidden jutsu but accidentally sends him to another universe (can't be replecated so no other naruto verse end up in Gotham)
He ends up in a strange place called Gotham city and he works out pretty quickly that chakra does not exist her( absolutely no charka, can't be replicated, copied, learns etc)
He becomes a vigilante by accident wearing his Anbu mask. They call him Gotham's Fox
He always has at least 5 shadow clones patrolling Gotham all the time.
People of Gotham love him and they make a group dedicated to helping him)
Helps homeless kids by buying them clothes,food,water etc and teaches self defense.
Cleans up the park for the kids, Visits hospitals secretly to help heal minor wounds (can't cure cancer etc)
He becomes an older brother/dad figure to Jason.
Doesn't get along with batman. (never)
Kills the joker and other vilians.