Jupiter is the largest planet within the Solar System. It has, also, managed to win a metaphorical lottery - it has several habitable moons (that offer the highest quality of life from all Outer System celestial bodies) and remains a vast treasure trove of natural resources. Unfortunately, this wasn't enough to stop its entire subsystem from devolving into the Solar System last remaining totalitarian regime. The Jupiter itself has actually been colonized - numerous cities are floating in its upper atmosphere, their inhabitants harvesting various valuable gasses from their planet. It is, however, merely ta footnote to the human civilization thriving throughout the subsystem. The low numbers and bad standard of life doesn't change the fact that it's a vital part of the Iron Pact's economy.
Jupiter was initially colonized by the terran predecessors of the Iron Pact, the western european fascists that have emerged as a superpower following the Days of Fire. While the Union of Progress and Freedom and the Alliance for the Preservation of Democracy succeded in blocking them from colonizing things closer to Earth, they eventually decided to go for a long-shot and moved all the way to the Jupiter. Which they promptly changed into their stronghold. Initially they only colonized some of the moons (namely, Himalia and Europa), but eventually this process expanded to other places of the Jupiter Subsystem, including the gas giant itself (although that's actually a development from the Golden Age of Mankind, and it was established at partially with the Solar Commonwealth's support). Jupiter back then was controlled by the Jovian Republic, an authoritarian republic that emerged following the first Iron Pact's collapse. Many considered it to be merely rebranded Iron Pact, ruled from the shadows by the descendants of the old ruling party. Those suspicions were proven correct when - soon after the Blackout destroyed the Solar Commonwealth - the Jovian Republic switched back into the Iron Pact, and has fully embraced radical policies of old.
Distance from Sun: 778.57 million km
Diameter: 139 800 km
Solar Constant: 0.073
Mass: 317.8 Earths
Mean Density: 1.326 kg/l
Day Length: 0.414 Earth days
Year Length: 11.868 Earth years
Rotation Axial Tilt: <10 degrees Avg. Temperature per Latitude
Type: Gas Giant
Location: Jupiter Subsystem
Population: ~9 mln.