oh yes, combos are possible too--- a little garden variety troll of darkness with a dash of ogre and deceptively silvery deep darkness of sorcery could very well make the leechlike vampire (I bet they hate that word LEECH.) Personally, my view, based on what I've seen is that we all have all the forms of darknesss inside us, but we also have predilections for our own favourite flavour. Just as we all have all forms have madness in us, but a definite leaning towards being more psychotic, neurotic, schizo, or manic/depressive. I even think we need these things inside us to stay sane.