[The Squatter of Amon Rûdh]

Even if there were other versions, Aragorn and Arwen simply don't use contractions. It wouldn't fit the style that Tolkien adopted when writing about them. Those quotations may be from a Babelfish translation, or typed in from memory; they may even be a misguided attempt to make the language "relevant to a modern audience" (i.e. modernised for the benefit of the illiterate). This is why my quotations are always copied from my books.