Eheh. Well, I guess if we're starting at level 4 playing an Efreeti bound by Aretmicia is out...
Given the fact that we already look like we'll be getting a spymaster and a vigilante, I'm leaning towards a magus Trifaccia who uses spell combat and arcane mark to etch arcane marks onto the bodies of the Queen's enemies, marking them as enemies of Korvosa/the Queen. Not sure whether I should dip into a single level of vigilante or pick up the Nameless One feat to better represent him just yet.
If I wanted to incorporate Kavazon's bloodline, I could pick up the Eldritch Scion archetype, but it would sacrifice both constant access to spell combat and the ability to effectively combine spell combat and metamagic.