I like the idea they fight to end a conflict. Maybe make it so he takes part in conflicts maybe to solve maybe to start depending on how Mars sees it.
You could also add some specifics to that. Maybe he's a defender of Western Civilizations (to emphasize the connection to Rome) or just humanity in general. Something like that would allow you to proactively engage in conflicts to further the safety of what he's defending.
Oh, and he'd probably hate the White Court. Butcher quite cleverly (imho) has them using Ancient Etruscan, and those were neighbors of the Romans who viewed them as rather decadent (though the Romans learned many of the trappings of civilizations from the Etruscans, but that's besides the point). As I understand it, the Etruscans probably weren't as decadent as some Romans thought (possibly it was just increased gender equality), but the White Court is so I say go with it.
