The Emperor is initially friendly toward Gulliver; he is hospitable and spares no expense in feeding him. But this all changes when Gulliver refuses to continue fighting Blefuscu and puts out a fire in the Empress's chamber by urinating on it.
Descriptions of the Emperor.
"His features are strong and masculine, with an Austrian lip and arched nose, his complexion olive, his countenance erect, his body and limbs well proportioned, all his motions graceful, and his deportment majestic."
"His voice was shrill, but very clear and articulate; and I could distinctly hear it when I stood up."