I'd like to see Two-Face again, done psychologically right.
First thing. Harvey suffered from a dissociation disorder. When he was abused by his father as a kid, Harvey shut himself off in a state of dissociation. He cut himself off from reality. So in that state, Harvey would have said
"Don't hurt him" to his father.
That was how he coped with the trauma.
So in great deals off stress, Harvey would revert to another reality in his mind to protect himself.
But what would go through his unconscious mind during his episode and conscious mind when the abuse and stress was over?
Hate? Anger?
So what is Two-Face? A split personality? No.
It is Harvey. Harvey merging with the thoughts and feelings he had in his numerous episodes.
Harvey's subconscious self merging with his conscious self. That coupled with his dissociation disorder. This has created new domiant personality traits to the already existing placid personality of Harvey. In his mind, Evil is stronger than good. Crime is greater than law and order. But like his personality, he realises that the two will remain in competition and neither will truly win over the other. This is because subconsciously, Harvey doesn't want to fully give in to his evil nature. That's the prime reason he has the coin.
The trauma of the accident has exposed Harvey to his subconscious thoughts and feelings, where he felt, deep down, was where evil lay domant.
So under the beliefs and stress of his accident, what it revealed to him, while triggering and couplimg with DID, Harvey became a new and fully aware personality, under the belief and effects of psychosis, that he was now 2 people.
That's why he refers to himself as we. Not me or him, but us.
But why become a criminal? Because he was mixed both with good and evil. However. While Harvey was formally good and worked for the forces of good, he as Two-Face was now exposed to his evil and corrupt nature. So therfore, he knew there was no place for a man like him in the forces of good.
But do I want to see him be a criminal and rob banks with 2 in the name?
No.
What I think makes the most sense is for Two-Face to wake up each morning and flip the coin to decide whether he will be a vigilante, killing criminals in the name of justice or committing crimes in the name of evil.
Even within being an anti-hero and killing evil in the name of justice is still a crime to law and order.
So sort of merging of Nolan's characterization with the comics.