Upright the King of Cups is read as emotional balance, diplomacy and wisdom exercised through compassion rather than through detachment; reversed, as moodiness, manipulation, or volatility beneath a surface that had looked composed.
As a person card, he is conventionally read as a steadying, emotionally mature figure, and readers commonly distinguish him from the Queen of Cups on the axis the Golden Dawn's structure formalizes, his Fire of Water an active mastery directed outward into counsel and diplomacy, her Water of Cups a depth held inward; the King advises and steadies others, where the Queen absorbs and reflects what she is given.
Waite's own printed meaning, a man of business, law or divinity, given to good and generous impulses, though also possibly double-dealing if the card falls badly, includes a warning of hidden duplicity that the moodiness and manipulation most contemporary readers now name is a softer, more psychological descendant of.
Because the Golden Dawn material behind his full title, the Lord of the Waves and the Waters, remained a restricted teaching document until Regardie's publication of the order's papers in 1937 to 1940, most twentieth-century readers reached this king through Waite's 1910 picture and keywords rather than through the older occult source, a pattern true of most of the court cards in this run.