A trusted minister should never harbor disloyal thoughts toward his lord.
Tips
usage
贰 is the anti-fraud capital form of 二. You see it everywhere on checks, bank receipts, and contracts because the simple 二 can be altered to 三 with one stroke. The standard banker's set: 壹贰叁肆伍陆柒捌玖拾.
history
Originally meant 'to duplicate / to second' - hence the secondary senses: a 贰臣 is a 'minister of two courts' (a traitor who served the conquering dynasty too); 怀贰 is 'to harbor a second heart' = disloyalty. The banker-numeral use is a Ming-Qing innovation that fixed it in modern finance.
Bottom 贝 (Kangxi #154, cowrie shell - ancient money). Anchors the character in commerce: the formal 'two' of money and contracts. Same radical drives 财 (wealth), 购 (purchase), 账 (account). Indexed under 贝 in modern lookup tables.
Top 弍 - an archaic 'two' element (two horizontal strokes plus a slanting stroke) - carries both the sound and meaning. It signals 'double / second' before the wealth-radical adds the bookkeeping context.
