As the superintendent of the O.S.N. in Sulaco, "Fussy Joe" is Nostromo's boss. He is most notable for being a windbag, reciting oodles and oodles of details about Costaguana's history—and, most importantly, his role in that history—to anyone who will listen.
He seems to believe that finding and hiring Nostromo was one of his biggest accomplishments of his life, and that he can take some of the credit for Nostromo's various feats and their impact on Sulaco/Costaguana. Nothing like being modest, we guess.