1)Time
2)Attention
3)Love
4)Cares about me
5)Listens to me/Hears me
6)Honesty/Trust
7)Ability to communicate
8)Ability to guide
9)Respect

i think that list is fairly comprehensive...up to a point. i did however number them for a reason, because i think they are semi-sequential. That is to say that i think they key part that sets the relationship away from any other relationship is number 8; a dom has a responsibility, with trust placed in them, to guide and help the sub grow...they cannot do it however, IMHO, without the other 7, which are necessary pre-requisites. (the love one is perhaps debatable, but certainly preferable).

HTH
sl