How would you describe the main characters from a mental standpoint in The Lovely Bones?

I think you have to infer a lot of this from what the
characters do and say in this novel. For example, with Mr. Harvey, we know he is a
serial killer, so his mental characteristics are typical of someone who lures children
to their death. Notice when he first runs into Susie before he kills her, how he is very
devious and sly - he tries to befriend her, even calls her by name (which she realizes
from heaven should have warned her, because he claimed not to know her name at the
beginning of their encounter). As the novel progresses, we see how devious he is in
pretending to be sorry about Susie's death, eluding the police, and even at the end,
where he is stalking another victim. Mostly, his mental characteristics are that he is a
pervert.

Susie's mental characteristics evolve over the
course of the novel. She is describing the story in retrospect, and she grows mentally.
In the beginning, she describes herself as a girl "with spunk" - remember the "Susie
peed on Lindsey" story? From heaven, she is upset about missing her family and
frustrated that no one can catch Mr. Harvey, but in the end, she comes to grips with her
situation and her mental state stabilizes.

If you go
through the novel like this, you can infer the other mental characteristics. Think about
what the characters do and say in their interactions with each other and how they react
to Susie's death. Susie's death, for example, has a different effect on her parents
because their mental characteristics are different. Abigail is somewhat unstable and
frustrated in her life. She is an educated woman who, with marriage, has had to forsake
her career so she becomes disconnected from her family. When Susie is killed, her grief
becomes unbearable and not knowing how to cope with it, she has an affair and then
leaves her husband. Buckley's mental state becomes one of childhood defensiveness as he
attempts to cope with Susie's death, but he is only 4 when it happens. Mostly, his
mother's leaving him upsets him mentally and emotionally, and when Abigail returns,
Buckley's mental state changes to one of anger and resentment against his
mom.

Mentally, Jack feels frustrated and guilty because of
what happened to Susie. He feels he has failed to protect her, but his grief spurs him
to become actively involved in trying to find Susie's killer. Plus, he has to be
mentally strong for the good of his other two children while coping with his own grief.
He is strong mentally as is Lindsey, who although she must cope with her grief over
Susie (to whom she was close), refuses to live the life of a victim and in the end, she
grows into a strong young woman, not an unfulfilled one like her
mother.