Those who wield the power over life and death have a tendency to crave control. They need to manage things in their life on a pathological level, and this need often grows into a desire to manage the lives of everyone else.
The most well known necromancer in Fellhollow was a man called Calius Waithe. He was one of the Children of Shadows until he decided that their policies of peaceful evil wasn’t what he was looking for. He was more an overtly evil sort of guy.
He decided, on one fateful autumnal eve, to raise an army of the undead and march them on Emberwood. He imagined the village cowering before him as he named himself their new king.