I'm not really into the EU. I kinda need a 411 on what is happening in the EU. I guess I can make a sacrifice on the sith. But I could just do one dark lord since there's no way there couldn't be just one dark jedi. He could have been under the separatists care until he turns old enough to take care of himself. And he could have be like in his 60s. Could have been trained the ways of the force until his masters death after a duel with star-killer. But I always wanted to make my own light-saber duel. He could be working for the separatist until the separatist realizes he's trying to take over him.
But if this can't work then It doesn't fit in. No big deal though. I'll think of something.