[Tom] was particularly clear and positive on one point, namely that he would punish everybody who deserved it: why, he wouldn’t have minded being punished himself if he deserved it, but then, he never did deserve it. (1.5.64)
This is a clear introduction to Tom, who was really arrogant even as a kid. Tom thinks that he is always right and can administer justice accordingly.
Maggie moreover had rather a tenderness for deformed things; [...] and she was especially fond of petting objects that would think it very delightful to be petted by her. (1.5.2)
Maggie’s compassionate nature and her love of the underdog is linked here to her desire for others to love her. She seems happy to love things that are most likely to love her back – such as a "deformed" creature who might be grateful for her attention.
It had been Philip’s first thought when he heard of the accident - "Will Tulliver be lame? It will be very hard for him if he is" - and Tom’s hitherto unforgiven offences were washed out by that pity. (2.6.8)
Philip’s compassionate nature comes through here. It is interesting that his grudge against Tom is only changed after he has a reason to pity Tom. Compassion often needs a nudge in this book, such as a crisis that can help people put a grudge, or anger, aside.
Maggie hated blame: she had been blamed all her life, and nothing had come of it but evil tempers. (3.2.23)
This is probably the best thematic summary of the book’s views on the need for compassion and forgiveness. It may be hard to do, but compassion is the morally right thing to do. Blame just seems to cause problems.
"But I won’t forgive him! I know what they say - he never meant me any harm - that’s the way Old Harry props up the raskills - he’s been at the bottom of everything - but he’s a fine gentleman - I know, I know. I shouldn’t ha’ gone to law, they say. But who made it so as there was no arbiratin’, and no justice to be got?" (3.9.29)
Mr. Tulliver’s climactic invective, or harsh speech, against Mr. Wakem reveals how hard it can be to actually forgive someone. Interestingly, Mr. Tulliver links the lack of compassion that the world has shown him to his current lack of forgiveness for Mr. Wakem. It’s sort of a vicious cycle of injustice and anger and blame.
"But it isn’t for that, that I’m jealous for the dark women - not because I’m dark myself. It’s because I always care the most about the unhappy people: if the blonde girl was forsaken, I should like her the best. I always take the side of the rejected lover in the stories." (5.4.10)
Though Maggie says her compassion has nothing to do with herself, this may not be entirely true. Maggie’s own suffering is what allows her to empathize with other people.
"You have no pity - you have no sense of your own imperfection and your own sins. It is a sin to be hard - it is not fitting for a mortal - for a Christian [...]. You thank God for nothing but your own virtues - you think they are great enough to win you everything else. You have not even a vision of feelings by the side of which your shining virtues are mere darkness!" (5.5.83)
Maggie’s climactic rant to Tom pretty much hits the nail on the head for his character. It is interesting that she casts Tom’s lack of pity as a moral failing and a sin. Tom’s lack of pity is more than a personality defect here.
"You dear tiny thing," said Maggie, in on of her bursts of loving admiration, "you enjoy other people’s happiness so much. I believe you would do without any of your own. I wish I were like you." (6.2.21)
Maggie praises Lucy for her good nature, but it is ironic, or amusing, that Lucy’s personal happiness is probably what allows her to be happy for others. As Maggie knows, it is much harder to look past your own suffering and be happy for others. It begs the question as to whether or not Lucy would be so happy for others if she didn’t have her own happiness.
"Faithfulness and constancy mean something else besides doing what is easiest and pleasantest to ourselves. They mean renouncing whatever is opposed to the reliance others have in us - whatever would cause misery to those whom the course of our lives has made dependent on us." (6.14.30)
Being faithful to others is a matter of compassion for Maggie. Her reluctance to cause others pain becomes a guiding moral principle. It is interesting that she notes how the "course of our lives" brings us into contact with these other people. Maggie says that she doesn’t get to choose the people towards whom she must be faithful and compassionate.
"O Bob," said Maggie, smiling faintly. "You’re a very good friend to me. But I shouldn’t like to punish any one, even if they’d done me wrong - I’ve done wrong myself too often." (7.2.48)
Again, Maggie’s personal experience as the victim or as someone on the receiving end of blame and anger causes her to forgive other people anything that they might do to her. But there are some self-esteem issues here too. Maggie won’t blame others, but she is often willing to blame herself for everything that goes wrong around her. Maggie has a guilt complex.