凉薄少年热血姑娘
[liáng bó shăo nián rè xuè gū niáng]
This phrase juxtaposes the cool-detached characteristics of a young boy ('凉薄少年', a boy with a seemingly cold personality or apathy) and fiery-tempered nature of a girl ('热血姑娘', passionate or fiery). This suggests contrasts coexisting in oneself or others: perhaps indicating two different types or temperaments that are complementary in a way.