I wasn't aware that you had a king for a brother.
我不知道你有个国王当兄弟。
解答:have +a/an+职位 for sb=有一个职位是由某人担任,介词for表示对象。
There's a letter for you.有你一封信。
It's a book for children.这是本儿童读物。
We got a new table for the dining room.我们给饭厅添了一张新桌子。
This is the place for me 这里很适合我。