Short answers, pulled from the story.
Duarte Barbosa (c. 1480-1521) was a Portuguese writer, interpreter, and officer who spent years in Portuguese India and later joined Ferdinand Magellan's first voyage to circumnavigate the world. He is known for writing the Book of Duarte Barbosa (c. 1516), one of the earliest examples of Portuguese travel literature, and for his role as a commander on the Victoria during the circumnavigation.
The Book of Duarte Barbosa, completed around 1516, contains detailed accounts of foreign cultures drawn from Barbosa's years living and working on the Malabar Coast of India. The original manuscript was lost for centuries and known only through the testimony of Italian writer Giovanni Battista Ramusio; it was rediscovered and published in Lisbon in the early 19th century.
Magellan married Beatriz, the sister of Duarte Barbosa, making Magellan Barbosa's brother-in-law. The connection formed after Magellan moved to Seville in 1516 and befriended Barbosa's father, Diogo Barbosa, both men having traveled to India.
Barbosa was killed on the 1st of May 1521 at a banquet near Cebu in the Philippines, hosted by Rajah Humabon. The banquet came just days after the Battle of Mactan, in which Ferdinand Magellan had been killed.
Barbosa learned Malayalam, the language of the Malabar Coast, after moving to Cannanore around 1502. He used that skill as an official interpreter, including serving Alfonso de Albuquerque in contact with the Rajah of Cannanore in 1503 and assisting Albuquerque's attempt to convert the King of Kochi in 1514.
Barbosa sailed from Seville on the 10th of August 1519 as part of Magellan's circumnavigation fleet. He helped suppress a riot at Puerto San Julian in Argentina on the 2nd of April 1520 and was subsequently made captain of the Victoria. After Magellan's death on the 27th of April 1521, Barbosa was named co-commander of the expedition alongside João Serrão.