Milla is so great. She's Milla Maxwell, the Lord of Spirits, who has taken a human body for a number of reasons. In particular she is on a mission to protect the world by destroying technology that kills spirits and threatens the balance of the world. And by destroying people who oppose her in this task as necessary. She's pretty much willing to do whatever is necessary! Xillia is pretty much the story of a whole bunch of humans getting caught up in her mission and swept along/inspired by her force of will. She basically never doubts herself or wavers in her resolve, and while there are some spoilers that means she has to reconsider some things, that always remains pretty much true. Meanwhile, she gets to know humans, since she's really very inhuman herself! But not in a naive robot sort of way, more in an interestingly alien way. Her body is a tool, she has no real concept of human relationships or emotional decision-making, etc. She's read a lot of books, though! Including books on sex and bondage apparently. . .

Also tell me about Ami.