Dude commited such horrible crimes that he was sentenced to rot in level 6.
Just recently we saw him implying that they should leave Hancock alive in order to rape her.
Dude has no redeeming qualities whatsoever.
He is one of the lowest pieces of shit that Oda has ever written and no, he certainly won't have an emotional backstory. He's one of those monsters that were just born evil (like Doflamingo).