R: Runes

Languages in fantasy and science fiction can be a tricky thing.  Most of us are not JRR Tolkien and willing and able to invent our own.  It's easier to invent a world if everyone speaks the same language and of course, for most of us, the words spoken are English.  An author can call the language something else, Hoochamochocha, if they want, but the words on the page are still English.

Sometimes, though, a writer can invent words and the new language is a device to convey something in the story.  For instance, in my book, Beyond the Gate, the hero, Cage Stone, has struggled all his life to learn writing and reading.  But on his journey through the mysterious caves beneath the mountain, he encounters words carved into the stones offering warnings.  The words are written in runes, a language unknown to humans.  But Cage is half elf.  After years of being embarrassed by his inability to read, he easily interprets the words written in the language of the elves.  During this time in the story, Cage is struggling with accepting his heritage for reasons you'll have to read the book to understand, and the relief he experiences in finally understanding written words in one more nudge down the path of acknowledging his mother's people.

Why other ways can an author use language as a device or plot point in a book?  Have you invented words or even more for something you're written? Do you enjoy reading books with invented words in and when does it become distracting to you?