IC: Dystopian Steampunk Setting
Okay so I'll talk mechanics first. You'll be starting at first level but you are a variant of gestalt characters so you will have a fairly large array of customisation options. I'm also not limiting people to paizo only material so you can get some interesting customisation from the get go. There also isn't any magic, it is all science. There are plenty of strange magic like abilities etc but it is all explained away by science.
For the setting you will be aristocrats of Skalsturm, a large city state, who are part of the various noble houses. Skalsturm and the other city states are being besieged by a species called the Uung though they are colloquially nicknamed Ug's or Raz's by the populace of Skalsturm. This species pushed the regular military back through the use of strange powers that completely destroyed the conventional tactics used by the military. The military was able to take a few Uung bodies back to Skalsturm for autopsy which lead to the discovery of what were effectively weaponised organs, these were then adapted by Skalsturm scientists and implanted into willing subjects. These people found great fame and fortune through various unbelievable exploits, and as such the noble houses jumped on this new trend. Soon after the scientists adapted the Uung organs the Uung poisoned the water supply and a virulent plague began to take hold of the populace of Skalsturm who were soon quarantined into the poor quarters of the city.