One weird thing about you I forgot to mention yesterday is that it's completely fine to use plural are in conjunction to it. You don't say "you is" something but "you are". This is remnants from the fact that the you was originally only uses for plurals.
There is also one common use for the old singular thee or thou. That is - when talking about God.
Language can be really interesting. Even the simple words you use every day can have an interesting history. I find myself often wondering these things. More often the more I write them. It's like they each tell a story of their own already alone.