I've fallen in love with a pronoun. "Thou", specifically. I've just finished reading a lovely book called Ella Minnow Pea, in which more and more letters of the alphabet keep getting outlawed, so after "u" is banned people have to call each other "thee" because "you" is impossible. It makes their dialogue so much sweeter.
I'm sad that we ever lost the word. I've always liked that older Christian texts address God not with the formal "You" as if to a superior, but "Thou" as if to a parent. The language that seems stuffy to modern ears is actually a mark of closeness, almost an endearment. Familial, intimate. "Be Thou my God" just doesn't work in modern speech. Joseph Campbell talks about the relationship between Native Americans and the bison, and how they addressed all living things as "thou". The whites came and called the bison "it" and slaughtered them. "The ego that sees a 'thou' is not the same ego that sees an 'it.' And when you go to war with people, the problem of the newspapers is to turn those people into 'its.'"
I've met a few old Quakers who still use "thee" - although they've developed their own grammar for it, which is a little distressing. The custom of using only the informal started in the 1600s when the Quakers began trying to break down class barriers, so refusing to address authority figures with the formal "you" and instead using the informal "thou" was quite a radical concept. Now it's almost never used with outsiders, so it's become a marker of intimacy and belonging - I've only ever heard it used within families or with other Quakers. Unfortunately it's now archaic because English happened to be a language that erased the informal entirely and started calling everyone formally.
The distinction still exists in other languages, of course, though in some places folks are veering (as we have in English) towards the formal and others towards the informal. The informal is almost always used in Danish now, but it still has a slightly closer feel to it because it sounds like the English. "Altid din" on the end of a letter is so much nicer when you read it literally as "thine" instead of "yours." I feel like Professor Bhaer (whom I had a crush on when I was eight) - "Say 'thou', also, and I shall say your language is almost as beautiful as mine."