Frankly it's very good.
Looks like we're watching a DC animated movie. Even so, I barely understand its power. (I'm in chapter 3)
The MC is like a new character, created especially to integrate the DC universe. Especially on Gotham, knowing for my part that there's more DC animation where Batman is present, than most of the other Justice League characters.
Like the latest movie that I recommend: Batman and Superman, battle of the super sounds. And also: Green Lantern, beware my power. he's good too even if it's not happening in Gotham.
And the fact that he starts as a criminal (at the beginning not intentional even naively and that following the events, he is taken part in the crime without exaggerating too much on his misdeeds). He has no relationship with Batman, except on his criminal activities which, as in the animated films, is normal.
Example: Batman pursues thugs and they end up in prison. And after the main plot begins, until Batman wins at the end of the movie. (that said the flim flashpoint is very good too)
Finally, just to say that so far (I'm in chapter 3, don't forget) the fanfic is really good and I appreciate this concept. I hope the author will continue like this.
And thank you for reading my comment because that's how I feel.
So !!!