Mad riddles

[Nimrothiel]

This one's a knock-off of a Mafia joke:

Three. One to screw it in, one to stand around looking heroic *cough, Legolas, cough* and one to kill the orcs trying to stop them.

Here's a new one:

What is coloured blue and green,
which elves consider a fair sight to be seen?
It is hostile to a tree,
yet a green leaf longs to see?

Bonus points if you answer with a line from the book.