English has one of the simplest grammars of any modern language. Only the pronouns retain distinctive subject and object forms.
Any English speaker who has completed from eight to twelve years of formal education ought to be able to master the forms and use of the personal pronouns.
The personal pronouns are I, me, you, he, she, it, we, us, they, and them.
It and you may be used as either subjects or objects.
I, he, she, we, and they are subject forms. These are the only forms that may be correctly used as the subject of a sentence.
Me, him, her, us, and them are the object forms. These are the only forms that may be correctly used as the object of a verb or a preposition
The following passage shows the use of personal pronouns to stand for nouns:
The knight rode to the castle. He dismounted and walked into the hall. It was filled with people. They were talking and eating. Servants waited on them. The knight saw a beautiful princess. She looked at him. He looked at her. “I want you for my wife,” he said. “You must come with my horse and me back to my father’s castle! Please, oh please! Come with us. We will protect you along the way.”
A common feature of non-standard speech is the incorrect use of pronouns. Television scriptwriters especially seem to be unaware of correct pronoun usage.
Note to fiction writers: Misused pronouns are a good way to indicate that a speaker is uneducated. It makes little sense, however, to use them in the speech of any character who may be presumed to have completed high school.