Hellva long Headcanon post
I like to preface this by mentioning that adobe-outdesign's theory of the Bendy that chases you in the game is Joey is the basis for this rp incarnation of Bendy, or "Bendy". Now, for the headcanons
Originally, Joey wanted to use Henry as the basis of "Bendy", however when Joey couldn't get in contact with Henry, and the discovery of that he had developed Post-Polio syndrome, Joey became desperate to live...
The ritual that Joey used to turn himself into Bendy was sabatoged. Exactly how or who did it is unknown at this moment.
The reason "Bendy" chases Henry, aside from some serious disproportionate rage directed at Henry, is the same reason why Joey wanted to use Henry in the first place for "Bendy". Joey becoming "Bendy" is surprisingly semi-stable. More stable then Alice but still has flaws. Namely? The bent and crooked legs, still being "off model" with five fingers, etc. Henry, being co-creator, would help "stabilize" Bendy enough to hypothetically make them truly become Bendy.
"Bendy" is blind due to Joey, in his late stage Post-Polio syndrome, going blind.
Pre-Polio Joey was a fantastic dancer. The lost of use of his legs might have been one of many factors into the descent into dark magic
Given in my headcanon, Henry was drafted, hence him leaving, Henry promised Joey to return to the studio when the war was over. He didn't, effectively starting the severing their friendship
Among "Bendy's" abilities are: Nigh invulnerability, teleportation in ink, shapeshifting (to a extent), super strength, can weild his ink to any use he desires, capable of forcing back other solid ink beings into "dark inky abyss".
While not exactly fast due to crooked legs, "Bendy" is surprisingly nimble and is capable of some far lunging.
Henry created the designs for the characters, but Joey had a knack for good characterization and writing.
When Joey attempted to turn himself into Bendy, the end result had....problems. namely, the mischievous trickster cartoon mind of Bendy ended up in the cutouts. The cutouts try to help Henry when they can but can't too much cause unfortunately they also act as "proxys" for "Bendy" to see through.
For the ink-toon-human thing to happened, the human self had to be killed. Boris' (plural) were stabbed in the heart, "Alice" (either Susie or Alison) had their throats slit. "Bendy" himself might have possibly deliberately drowned himself in ink....