Plot guide line to follow: FOLLOW THEM

"I've been told plenty of times I'm a monster - it's time to prove them wrong. Even the devil knows that's a compliment."

Her friend was one of many to die at the hands of the Winchesters. Another splash of blood on their red stained hands. They didn't seem to care, didn't seem to realise that the girl they killed left people behind.
She left Ebony behind.
It wasn't going to be easy, but Ebony was going to make them pay.