You

"The fact that you follows closely behind I in popularity is probably attributable to its being an eight-way word: both subject and object, both singular and plural, and both formal and familiar. The all-purpose second person is an unusual feature of English, as middle-schoolers realize when they start taking French, Spanish, or, especially, German, which offers a choice of seven different singular versions of you.

It's relatively new in our language. In early modern English, beginning in the late fifteenth century, thou, thee, and thy were singular forms for the subjective, objective, and possessive, and ye, you and your were plural. In the 1500s and 1600s ye, and then the thou/thee/thy forms, faded away, to be replaced by the all-purpose you. But approaches to this second person were interesting in this period of flux.

David Crystal writes in The Cambridge Encyclopedia of English that by Shakespeare's time, you 'was used by people of lower rank or status to those above them (such as ordinary people to nobles, children to parents, servants to masters, nobles to the monarch), and was also the standard way for the upper classes to talk to each other. By contrast, thou/thee were used
by people of higher rank to those beneath them, and by the lower classes to each other; also, in elevated poetic style, in addressing God, and in talking to witches, ghosts, and other supernatural beings.' The OED cites a 1675 quotation: 'No Man will You God, but will use the pronoun Thou to him.'

"Needless to say, this ambiguity and variability were gold in the hand of a writer like Shakespeare, and he played with it endlessly, sometimes having a character switch modes of address within a speech to indicate a change in attitude. Crystal cites Sir Toby Belch's advice to Sir Andrew Aguecheek, in Twelfth Night, on how to get under the skin of an antagonist: 'if
thou thou'st him some thrice, it will not be amiss.' Sir Toby, of course, is himself thou-ing Sir Andrew."'

Ben Yagoda, When You Catch an Adjective, Kill It, Broadway Books, 2007, pp. 202-204.