Disclaimer: The Colonnas are appropriated from actual history with flimsy sources and alterations for the purpose of the game. No offense is intended to the modern-day Colonnas (who have taught me that the Vatican still has hereditary princes.)
The Colonna Family is a noble family hailing from Rome. They reside in a series of buildings at the foot of one of Rome's seven hills and control rural land and roadways in the south of Rome. Their line has produced many cardinals and other religious officials and has a beef with the current papacy in Avignon, both for former conflicts (the Pope agreeing to disinherit/exile members of its line in favour of others), political reasons (their rivalry with another noble family, the Orsini), financial reasons (the lack of a Pope driving tourism away from Rome), and the corruption rumoured in the current papacy. They have a powerful cardinal for a family member currently stationed in Avignon.
The branch of the family that Marsilia was born to is headed by Mazzeo Colonna, a third son, and his wife Dianora. This family branch owns a fine estate by the Via Casilina and has some prestige but is not high in the line of inheritance. Mazzeo oversees trade coming in from the port and some number of farms. Unfortunately for him, he has failed to produce a single male heir; Marsilia is his fourth daughter. She has three elder sisters: Amata, Florese, and Iuliana. Amata is rather plain; her dark hair frizzes rather than curls, and she grows hair on her upper lip. She's soft-spoken and a good cook, though, and has been married off. Florese is engaged and the estate is currently bustling with the plans for her marriage; she is passably pretty and good with a needle, though also utterly full of herself. Iuliana is only one year Marsilia's senior and has not yet been entertaining marriage offers; she's a bit dim and is unlikely to be of much use managing a household, but she laughs at everything and has childbearing hips. They all agree she'll be the happiest mother, so long as she doesn't marry a cruel man.
Some men might be spiteful with their wife for the lack of an heir, but Mazzeo respects his wife; she is excellent at managing finances and gives quite good advice. She also works to maintain correspondence with influential people and is an excellent host, which has brought some prestige to their home and good marriage prospects by to see their daughters, although neither of them has been hurried in marrying them off.
Perhaps for these reasons, Mazzeo has indulged Marsilia in her wild tendencies to dress as a boy and pursue education over other more realistic pursuits of cooking or sewing; he imagines she will either become a nun, with her dedication to prayer, or that she will at least be attractive enough that her wild nature will not put off a spouse. Given that he already has three other daughters for marriage prospects--but no real chance to further his immediate family's lot in life, since the heir to his estate is an elder brother's son--he worries more about family politics on a broader scale and the day-to-day workings of his affairs.