The Crooked Man wears a bloodied white undershirt and jacket. His most prominent feature is his neck, which is completely bent, to an extent it looks like an elbow. He has a pair of hollow, black, eyes and a wide and creepy grin on his face.
If his facets and the notes he wrote during the course of the game are to be believed, Duke was a idealist young man who due to his troubled past (being abandoned by his mother, failing to become a lawyer and being dumped by his girlfriend) eventually became depressed and eventually committed suicide.
After becoming a vengeful spirit, he becomes resentful and upon seeing David, he immediately dislikes him. The reason he follows David is because he hates him for being so much like him and wants him to die for it. And because some part of him wants David to not go down the same path he did and end up like him.
As the Crooked Man, he generally goes after David, but if Sissi, D or Fluffy are around he prefers going after them and trying to kill them much to David's confusion. After it is revealed that the three of them are facets of Duke, it makes perfect sense. Sissi has regrets over lost love, D has regrets over failed dreams, and Fluffy's been abandoned. These are all the aspects of Duke that ultimately led to his eventual suicide.
- The Crooked Man represents Duke's resentment and despair. However, during Stage 3 there is a note from an otherwise-unrelated man who killed himself in order to get away from...something. David also says that he's been hearing "voices" in his head, long before the Crooked Man started coming for him. The Crooked Man in the game is Duke's, but apparently he's had one of his own for some time and it's part of the reason Duke decided to step in. It's even possible that the creature who tries to make David shoot himself in Stage 4 was David's own Crooked Man, not Duke's.