Answer:
What is often returned but is never borrowed?
What is so fragile that saying its name breaks it?
Useful tool for who in darkness dwell. Within you, corrupting like a deadly spell.
Do what he says and you'll be fine, don't and you lose the game.
Three little letters, a paradox to some. The worse that it is, the better it becomes.
I am free the first time and second time but the third time is going to cost you money.