Answer:
Two in a whole and four in a pair. And six in a trio you see. And eight's a quartet but what you must get. Is the name that fits just one of me?
I hide but my head is outside.
What looks back but cannot see?
Bold are the first; true are the second; playful are the third; clever are the fourth; forceful are the fifth.
Always wax, yet always wane: I melt, succumbed to the flame. Lighting darkness, with fate unblest, I soon devolve to shapeless mess.
What never gets any wetter no matter how hard it rains?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?