look at the charecter stitistics (mispelled), in 7 all the chaecters seemed human 9even red XIII, who wasn't) in 9, each individual charecter has he/his own goals and opinions about things, their own agendas, and each one contrasted the other.

steiner wanted to kill zidane (basicly)
steiner how ever did work with zidane to protect garnet.
steiner got along great with vivi, who was great pals with zidane
garnet and zidane had a lot of friction between them, but the still wanted to be near eatch other.
which then puts itself back at the top of this list

i wont add the other four into this mix cause my brain would blow up.....