bear ill will (/malice); bent on doing evil;be up to no good;cherish(/harbour)evil designs;have bad intentions;with hidden intent; with sinister (/ulterior) designs(/motives) ❍ 我觉得他们真是～，我如果不先采取措施，后害实在无穷。(爱新觉罗·溥仪《我的前半生》150)I now felt that they were completely unreliable and that if I did not strike first there would be no end of trouble.
居心叵测ju xin po ce
with sinister design
居心叵测
with sinister design;with ulterior motives
居心叵测jū xīn pǒ cè
居心：存心；叵：不可；测：推测。存心险恶，难以推测。with concealed intentions, bent on doing evil, cherish dark designs