Forgive me if I'm wrong, but I disagree totally with the idea that 
Victoria and (Quaxo) Mistoffeles are an 'item'. Don't you see them 
rather as brother-sister? I mean, they have the same color fur 
(Quaxo's face and paws are the same pure white as Victoria's coat) 
and they can be found together in most of the dances. It's also my 
opinion that you could add Alonzo to that little sibling group, but I 
could be wrong there.

I think to prove my point there are three obvious parts in the movie,

1.) Right after Victoria's solo dance, although that could be 
disputed.

2.) During Gus' song. The two are sitting next to one another and at 
one point Victoria leans back as if to say, "Okay, bored now," and 
Quaxo sort of taps her on the back and says "hey, show some respect".

3.) After Victoria's initiated the acceptance of Grizzabella into the 
group. The first person she leads the old cat to is, guess who, 
Mistoffeles (and then Alonzo), and I can imagine her saying "I'd like 
to introduce you to my brother..."

I thought the two were a pair at first as well, but watch the movie 
again with this in mind. It seems to be a bit different.

- Raiden