He bowed slightly to K.'s uncle, who appeared very flattered to make this new acquaintance, yet, being by nature incapable of expressing obligation, requited the Clerk of the Court's words with a burst of embarrassed but raucous laughter.
to return in kind; to repay; to recompense; to reward
الواصلة
to re·turn in kind; to repay; to recompense; to re·ward