Will be something like Assassin's Creed 2, Brazil was a Portuguese colony and in 18th century (1808), the royal Portuguese family was escaped from Napoleonic wars and set an empire in Brazil. They transform Rio de Janeiro in a metropolis like Lisbon.
In 1822, the royal family was back to Portugal, but his older son, Pedro, stay in Brazil and he has declared an independency of Brazil. In his reign, many conflicts were occurred and he resign and back to Portugal.
Your son, stay in Brazil, but he was very young to claim the throne. The empire of Brazil was ruled by regents and again, we had to much conflicts. But when Pedro II complete 18, he claimed the crown and his reign was more peacefully, Brazil was made so many progresses but when the realm was decides abolish slavery, the elite conspire with military and make a coup, declaring a Republic of Brazil.