I was wondering a bit on technology: I'm assuming we're far enough in the future (or far enough away from established science, anyway) that terraforming is possible, and has been successful on at least some of the stellar bodies in the Sol system. Is it then too much of a stretch, say, for humans to live on Ganymede without the use of enclosed environments/atmospheric domes and so on? Because that's kind of the assumption I went with.
But anyway:
Ruling House of Ganymede: O'Brien-Bonaparte-Stuart (referred to informally as "The Royal House O'Brien")
Territory: The Kingdom of Ganymede
History: Among the younger ruling dynasties in the Solar System, the O'Brien clan traces its beginnings three generations back to James O'Brien, a human born on Earth. Well-educated and utterly unscrupulous, O'Brien was in his time notorious as the most skilled and cunning thief alive. After stealing priceless art and artifacts from dozens of museums, and breaking out of nearly as many prisons, he declared that the challenges of Earth "bored" him. Striking out for Ganymede, a moon of Jupiter then in a state of anarchic flux, he produced papers detailing his lineage, and claimed descent from several notable human royal lines. Gaining followers by both his wealth and his exceptional skill at oratory, he rallied the populace and seized control of one of the poorer locales in the system. Now remembered as "Mad King Jim," he is celebrated as something of a folk hero by the common people, a perception encouraged by the ruling regime
The O'Brien's generally regard themselves as outsiders relative to the other dynasties, feeling themselves looked down upon by the rulers of wealthier, more populous territories. This is especially true of Jupiter, whose denizens are seen as untrustworthy and decadent. It is not uncommon to see a member of the ruling court suspiciously make the sign of the horns toward Jupiter, when the planet fills the sky with red. Although monarchs in name, the King is held in check by a written constitution, and can theoretically be deposed by the Great Assembly, a unicameral legislature. This notion to popular sovereignty is alluded to in the title "King of the Ganymedians," who rule the people as citizens, not the land itself as despot. In practice the monarch has a somewhat greater degree of power than most constitutional rulers, being the chief executive, the commander in chief of the military, and having the unilateral power to declare war, negotiate treaties, veto or even dissolve the Assembly, and to raise commoners to noble rank.
Name: HRM James III Patrick Napoleon O'Brien, King of the Ganymedians
Age: 43
Race: Human
Gender: Male
Appearance: Of middling height, and balding. Fair-skinned, with receding brown hair, making something of a half-tonsure around the rim of his head. Dark blue eyes, ruddy face. Growing fat around the midriff. Generally dresses simply, favoring a military-inspired uniform of Lincoln green with brass buttons and black piping.
Personality: Cautious and calculating, James O'Brien seldom acts impulsively. All his plans are laid well in advance, both the malicious and the benevolent. He is by most accounts a decent man, and above all an honorable one. Pride is his sin, certainly, and one for which his people in general are well known. He enjoys a drink now and again, but is not one for parties and social affairs, preferring quiet, intimate gatherings. He takes great interest in the Ganymedian military, and has been known to personally inspect regiments, berating officers and barking orders if things are not to his liking. More than once he has led impromptu parade drills, personally directing troops by waving an antique saber.
Name: HRM Marianna Sophie Murat O'Brien (nee Orléans), Queen of the Ganymedians
Age: 37
Race: Human
Gender: Female
Appearance: Taller than her husband by nearly a head, the Queen is of an athletic build, with straight blonde hair falling past her shoulders, currently dyed lime green. Her eyes are light brown, and her face long. Her features are somewhat plain, but not repulsive. She dresses most generally in uncomplicated, brightly-colored gowns, having a particular fondness for pastels.
Personality: Much like the King, the Queen is also the careful sort, though is somewhat less averse to the occasional moment of spontaneity. Up-beat and energetic, she attempts to fill the social void he leaves in the Court, frequently hosting parties and sponsoring concerts of traditional Earth music. Possessed of a sharp mind and an excellent education, she occasionally debates courtiers and philosophers on the finer points of theology, political theory, and economics. She also attempts (with less success) to set style trends in the court, which most recently led to her current hair color.
Name: HRH Catherine Marianna Victoria O'Brien, Crown Princess
Age: 19
Race: Human
Gender: Female
Appearance: Of fair skin and curving shape, Princess Catherine is widely regarded by the noble families of Ganymede as a desirable match for their sons- and not just because she stands to inherit her father's Kingdom. Her dark blonde hair is cut short, a little shy of her narrow shoulders. Her eyes are dark blue, and hide mischief. She is of average height, and has rather large feet. She dresses not unlike her mother, in simple dresses, though instead shows a certain preference for earthen tones such as brown and dark green.
Personality: In a word, headstrong. Such is not unusual for young men and women, though Catherine can be a bit much for those unfamiliar with her. She is adventurous in the extreme, judging any day on which her life was not risked a dull one. She is particularly fond of collecting several other young nobles from the court, withdrawing to a family lakehouse, drinking heavily, dancing a little, and then engaging in fencing contests. Or swimming, hunting, or driving around. Whatever the crew is up for, really. Knowing that her parents seek to marry her off to make an alliance with another noble family, probably foreign royalty, she intends to have as much fun as she can beforehand.