Much as I adore Eiko an' Vivi, my vote went to Steiner. When the game first started off, I completely hated the guy. I remember thinking how creepy and annoying I found him to be. Don't exactly know how it happened, but at some point during the story, I found myself tolerating him. Then, outta the blue, he became one of my favorite characters of the game. O.o Go fig, ne?

Long live Steiner!