fair-haired boy 意思是“受宠的人；红人；宠儿”（多用于贬义） 。

【例句】
The new intern quickly became the fair-haired boy of the team, impressing everyone with his skills and work ethic.
新实习生迅速成为团队的宠儿，用他的技能和职业道德给所有人留下了深刻印象。

My oldest brother is definitely the fair-haired boy in our family—he can do no wrong as far as our parents are concerned.
我最大的哥哥是我们家庭里特别受宠的人，在我父母看来他做的事情没有是错的。