It is unknown who he was back then, but now, he is a dark secret who hides under Bracer's shadow, watching and waiting for the moment to emerge from the shadows.
He has a similar appearance to Bracer, but he is not to be confused with him. He has the similar body and structure of Bracer, except that his face only consist of a dark mass with red blinking light for eyes, he also has the signature hat to Bracer, except that appears to be dark red. He also appears to have rows of sharp teeth, although it looks like he only has one row.
It is unknown how he acts or does, that is because he never reveals himself to anyone else except for all Bracer versions, because he believes that he should stick to own kind, he would normally be misunderstood as a threat, that's because he is a threat! He often would attack people during the night just to show the world what he capable of.
Bracer - He talks with him the most because they both have dark secrets which they keep to themselves, so despite killing people for an unknown and odd reason, Bracer considers B-0 his "blood brother".
Toy Bracer - He talks with him sometimes, that's because people often talk about Toy Bracer, so B-0 doesn't talk with him because he knows Toy Bracer will accidentally reveal B-0's existence, so he doesn't talk to him mostly.
Phantom Bracer - He talks to him just as much as Bracer, because he is a phantom of his blood brother, so they talk much at times. They often share similar ordeals and much more, so these 2 are a forgotten duo.
Nightmare Bracer - He likes N.Bracer's way of killing people and they talk and share tactics of killing people, they often work together and murder people, this proves that 2 killers make a killing spree.
Any facts or ideas on B-0 are currently unknown