Epic Road Trip Tale

Hello all!!

I am new to , right now I am constructing an epic tale of a duo(sorta) bounty hunters who travel cross country to reclaim souls in order to pay a decades long debt.
Now I pretty much have the first protag figured out - my issue lays with the second protag. I feel I might have neglected the second protag so I need some one else to help turn him into a complex character.

So I'll just give you a checklist about the story. I[m also open to plot ideas.;
Bounty Hunters(Demon Dogs) shape shifters
Eternally bound to the deal making demon

The First protag is a woman -

So what are you asking for here? Do you need help choosing what the characters look like ? Or...? It was a very confusing description of what you need.