Finn is part of a series of characters who are inspired by musical theatre adaptations of classic literature. In this case he's inspired by Bill Sikes from the musical Oliver! as opposed to the original Charles Dickens version.

Finn's similarity to Bill Sikes is mostly just related to the character archetype and the (to me anyway) obvious name reference. He's got elements of Jack the Ripper and Carl Panzram as well. He's basically a 19th century gangster whose been mucking about for far too long. Underneath that hard exterior, there's a big softy, though very few get to see it.

Art by  Wooy