Just for you I've written to Robert Beltran. (actually from an interview with him post-'Endgame')
"I [Robert] wanted to know more about his [Chakotay] past. We saw his father, we saw his grandfather, but we never saw his mother. Did he have a sister? Was he ever married at some point? What kinds of relationships did he have with other women before Seska? And I would have liked to have seen a little bit more relationship development with the other characters on the ship. Mainly, though, I wanted his past fleshed out more than it was."
(It then goes on about a specific relationship developed more fully in 'Endgame', which everyone probably knows by now, but I won't reveal just in case.)
I think he speaks for us all there, about his character needing more 'flesh on the bones', you would have thought that in seven years we would have learnt a little more. Can you think of any TNG or DS9 characters that we know so little about.