Fi: Brandon lives by a strict personal moral code that he never violates. He sometimes compares others to his own morals and finds them wanting (particularly, Willoughby). He is aware of how he responds in certain situations and asks for distractions to avoid them. Brandon enjoys expressing his own opinions, both to encourage others to strive to do their best (giving Marianne a difficult piece of music, to expand her talent) and in criticizing them (failing to fawn over her playing).
Ne: He sees an opportunity to become familiar with the Dashwoods and strengthen his connection to Marianne and takes it, by frequently dropping in, inquiring about her health, and bringing her gifts. Brandon immediately senses the connection between Marianne and Willoughby, and it concerns him enough to inquire after the young man’s intentions.
Si: Music is one area of interest, and he is very knowledgeable about it. Brandon’s curiosity toward Marianne and Willoughby relates to his distant experience with the loss of the woman he loved, and her unfortunate life at the hands of a cad. He remains faithful to her memory until he meets Marianne, whose passion, intelligence, and sweetness remind him of his first love.
Te: He does nothing without purpose, and all for a cause. Brandon springs into action when it becomes known that his ward has been discovered. He takes deliberate steps to protect her and avenge her abandonment. He purchases and sends a piano to Marianne, and follows through on his courtship with gentle determination.