Why does the pronoun you break all the rules?

Imagine you see one jovial-looking chap.  You might say:
He is happy.   (singular, 3rd person)
And if there are two, you might even say:
They are happy.  (plural, 3rd person)

When you are talking to them, you would say:
You are happy.        (singular, 2nd person)
You are happy.        (plural, 2nd person)
Why not you is?

If you were back in the 1400's, you might have said:
Thou art happy.         (singular, subject, 2nd person)
Ye be happy.              (plural, subject, 2nd person)
I love thee.                (singular, object, 2nd person)
I love you.                  (plural, object, 2nd person)

So, you was actually for multiple objects.  As the language changed, it became the formal form for all of the above cases and then eventually consumed them all.
These days, we do not use thou, thee or ye.  And you has become the pronoun for both subject and object positions.

It also holds the title for addressing both one person and crowds.  Many languages have two seperate words and colloquially, we fill this missing lexis with you guys or y'all for the plural form to make it clear that we are speaking to everyone not just one person.

Is bilinguism becoming the norm or are we just starting to notice it?

Just a quick thought for the day:

With only 212 countries in the world, but about 6000 languages.  It seems that bilingualism and multilingualism are actually the norm.  When I was growing up it seemed that everyone I knew only spoke one language but these days monolingualism seems to be the unusual state.
The number of languages is decreasing at a rate of one every 14 days but those that remain are becoming more and more spliced together through borrowing and exposure.  With English being the complex language that it is, is it really the best candidate for the one language?  Especially given that more people speak Mandarin?
Or will we see a slow process of fusing the languages together into one composite language? 

What kind of language do you speak?

So we often think that texts are broken into paragraphs which are broken into sentences and then into words.  But what are words broken into?
We know that a word can be broken into syllables but that is a practice for dividing the sounds up; if we are looking at meaning, we need to break it up into meaningful chunks where the word unbreakable for example becomes un (not), break and able (possible).

These are morphemes. 
A word is broken up into the chunks that add meaning to the word.  Now we can understand a way that linguists use to classify languages.

Isolating languages
These languages add the meaning to the word by surrounding it with other words.

Polysynthetic languages
These languages use affixes to add on to the base word.

So which one is English?  Neither.  And both.
Actually, we need to think of it more as a spectrum into which most languages fall in the middle or tending toward one extreme or the other.

Take the word "sing".  If I want to show my ability to do this, I add "can".  This is a separate word.  But then if I want to show that this is my profession, I add -er to make "singer".  This is a bound morpheme (the -er cannot stand alone).

It is an interesting difference to note when you are learning a new language or trying to understand the errors of someone else.