Here's a few song suggestions I thought of when looking over the profile:
Ennio Morricone's The Good, The Bad, and The Ugly. I don't know why I thought of this song, but it is just stuck in my head when I see the icon. I could totally imagine him in a flintlock standoff with someone else.
Breaking Benjamin's I Will Not Bow. After reading the backstory for this character, I feel this song definitely fits. The lyrics "And I'll survive, paranoid, I have lost the will to change," I think fit the most.
Johnny Cash's God Will Cut You Down. I definitely think this fits the motif of the character, a cold and ruthless killer, devout in faith and merciless in execution.
v HOLY COW THESE ARE SO GOOD. Ship in a Bottle is incredibly accurate to his lore, 555 is very indicative of the façade he puts up for his government as an ambassador, and Olive Branch's subtle irony is just beautiful. (I remember seeing Olive Branch used in the car chase scene in the Lackadaisy Pilot)