Answer:
The negative hero in each story
There is one in every corner and two in every room.
A tasty reward given to well behaved dogs and kids
Doing something of this nature is likely to land you in court
A job that involves sitting in a highchair, wearing a black gown and smacking things with a mallet
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.