Oriencor Falcrest is a black Númenórean, whose family was run out of their ancestral home centuries ago and forced to live in secret near the Tower hills. Specializing in sanguimancy, she slew her own family when she came of age and found that living on the blood of others kept her own youth and vitality from failing her. She grew so bold that she began preying on elves, and even thought she could match the likes of Elrond.
She was wrong, and was very nearly destroyed by him. Forced to retreat to her keep in shame, she has spent the last handful of decades rebuilding her power and plotting her vengeance.
Note: This is an original character for The Hobbit/Lord of the Rings universe.
It did well enough to stay on its own track without getting entangled too deeply in the sub-plots going on behind the scenes, but I think you're definitely right.