Gio is friendly, outgoing, emotional, excitable, overconfident, arrogant, brash, self-doubting, mercurial and moody in turns. Joy in the morning can turn to depression in the afternoon and a happy medium reached by midnight. In short, he is a teenage boy. He preens like a peacock in front of the opposite sex and puffs up like a cat in the face of male rivals.
He falls in love quickly, always convinced that this girl is the one, then falls in love just as quickly when the next one comes along. He stores up slights from other young men and broods on them, saving up past wrongs to avenge at some point in the future. Again- a teenage boy. He is young and has yet to really be hurt by anything or anyone, insulated from responsibilities by his family's money and his older brothers' successes.
Gio has a small number of loyal friends and a wide network of other friends, acquaintances, and people he knows well enough to call by name. He's generally friendly and eager to make new friends, and naive enough to think the best of most people.
He has never really been engaged by anything, from schooling to sword fighting to poetry to horses. That isn't to say he's unintelligent or unmotivated, just that he's never been pushed because he's never really needed anything that his family's money couldn't get for him.
Gio has few exceptional skills, but is a very good gambler, has an excellent palate for wine, and is looked to by his friends for his sartorial expertise. He is a middling fighter, able to hold his own in a brawl but not stand out in a fight, and only a passable sailor and rider. Having grown up in Venice, he knows the canals and bridges like the back of his hand, though his knowledge of the city is understandably concentrated in the better parts.