绵里藏针

1. • lit. a needle concealed in silk floss (idiom)
2. • fig. ruthless character behind a gentle appearance
3. • a wolf in sheep's clothing
4. • an iron fist in a velvet glove

Character by character

• 绵(mián)silk floss
• 里(lǐ)lining
• 藏(cáng)conceal
• 针(zhēn)needle