Lightened, then dyed dark -can I do black demi?

That about sums it up, my hair was lightened to very light blonde (some strands were practically white).  I dyed it medium brown last week using permanent dye and 20 volume developer.  (My hair is so fried its sad).  Its already fading a little, but is still a lighter brown.  Obviously, my hair is very porous, and I do expect more fading.

So, some questions: 
   - What will happen if I use semi or demi permanent dye that is black?  Will the black hang around too long so that I get lighter roots, or will it wash out way too soon?  (I don't want lighter roots later, I'd like it to wash out, but it doesn't seem worth doing if it doesn't last longer than a week.)
   - I see they make special developer that says its for demi-perm, should I use that instead of 10 volume developer? Is it equal peroxide to 10 volume?  (Thinking about damage).

Nope, I'm not a pro, so I don't know everything!  People have complained many times here that black can be so hard to get rid of - I wasn't sure about this situation.  Thanks!    How long does your Ion red last?