Passive depressive behavior is characterized by a melancholy and pessimistic manner that indicates depression or, in more general terms, expressing depression in a subtle, passive or indirect way.
When the passive depressive person reaches out for attention by complaining publicly about said depression, and when someone responds to their complaint, the passive depressive person says something mysterious like "you just won't understand me and my complicated mind".
Did you see Brian's Facebook status today? He was so passive depressive! He should just tell us why he is feeling so down instead of crying out for attention and posting dumb emo lyrics.