Everyone, like my new avatar?
Joining the heated debate, I guess that Ice-Hawk refers to the following picture below:
For Lucy to pay for her crimes.
However, I don't want to talk much about the morality issue.
Except when she killed the second family in episode 9 due to jealousy. She eavesdropped the mother and little kids laughing and enjoying their family time.
Because Lucy never experienced family love but rather frustration and desolation, she vent their anger upon that family out of pure envy.
She could not accept or tolerate the idea of someone else spending a happy time, therefore, she wanted them to feel miserable in order for Lucy to feel less miserable; conclusion waste them right away.
And how is it that Lucy does not views herself as a human?
She shows despair, sadness, envy, anger, frustration, grief, and wants to seek out for just a happy moment. If you ask me, that's pretty human feelings and behavior.
And also when in the last episodes she means that humans are foolish, but in doing so she also insults Kouta due that he's also human. Condradictory paradox, don't you think?