Woo, first vote! I think that even though Nadia was on Alias for a season and a bit, I think her background is still a bit foggy, so I would always love to know more about her past and such.
I would've loved to see more of Anna Espinosa, Sydney's arch nemesis. I voted for her, but that doesn't mean that I didn't want to see more of Nadia or Weiss.
Roberto Fox was in "The Orphan" in season 4. He was the one who recruited Nadia to work for "Argentine Intelligence" when she was on the streets...but he wasn't really Argentine Intelligence...much like her sister's past...yeah.