My brother(doing的逻辑主语) coming back tonight(独立主格结构做状语), I (主语)have to(和后面的pick up一起做谓语) pick him(pick up的宾语) up at train station(地点状语),as a result of(原因状语) which(状语的宾语),my (定语从句doing的逻辑主语)being late(定语从句的主语) at the party(定语从句的主语的定语) appears(定语从句的谓语) an inevitable reality(定语从句表语).
翻译: 弟弟晚上回来,我不得不去火车站接他,结果,我聚会迟到似乎成了不可避免的事实。