Finley's reference from his primary universe
He's a lesser-known subset of lust demon known as a concubus, rather than an incubus or succubus. This is relevant to his story but I won't go into too much detail XD
Anyway, his lower-back tattoo is also his mark which signifies his ownership to his Devil, Dwi. Pretty much every demon who is on earth works under a Devil.

Finley himself quite literally works, He works at a strip club called the Underworld as a private dancer, pole dancer (and sometimes stripper) and bartender.