Answer:
I occur twice in eternity. And I'm always within sight.
Hearing something unexpected or touching a live wire can have this effect.
They come in many varieties: Red, Black, Dead, and Caspian to name a few.
What never gets any wetter no matter how hard it rains?
What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?
What goes around and around the wood, but never goes into the wood?