"He took care of my brother and I." "He took care of my brother and me." Which is correct? Remove the non-self part. "He took care of I." "He took care of me.

"He took care of my brother and I." "He took care of my brother and me." Which is correct? Remove the non-self part. "He took care of I." "He took care of me." "Me" is correct because it's the object. ---- "My brother and I climbed a hill." "My brother and me climbed a hill." Which is correct? Remove the non-self part. "I climbed a hill." "Me climbed a hill." "I" is correct because it's the subject. ---- This is a real grammatical rule. It is prescriptive, that's what grammar means. You can keep not believing it, but that does not make it any less true.