The Corsican Brothers is a novella by Alexandre Dumas, père, (1802-1870) detailing a visit by the narrator to Sicily and meeting with one of two twin brothers and his return to Paris where he meets the other brother. What makes the novella interesting reading is the way it combines a narrative plot with a travelogue, detailing the experiences of the narrator in a land distant from his native France, and exotic in both setting and culture.
The first element of family expectations we see in the novel is that of hospitality to strangers. The families of the area are expected to offer travelers free lodging and food. Doing so brings good luck, and not doing so is regarded as rude and barbaric.
The second major expectation is extreme loyalty to the family and the tradition of "vendetta", pursuing family feuds and vengeance until either a settlement is negotiated or the entire family on one side of the feud is dead. These feuds are described as violent and often started over trivia (a strayed chicken in one case) but escalate quickly due to a conception of family honor that requires uncompromising retaliation for even the smallest slight.
While Lucien is very much part of this culture of vendetta and glories in his prowess with weapons, Louis is a much milder character who nevertheless gets killed in a duel.