Quote 13
"Frankenstein! you belong then to my enemy--to him towards whom I have sworn eternal revenge; you shall be my first victim." (16.30)
Notice that the monster thinks of William as "belonging" to Frankenstein. He doesn't seem to see much difference between killing William and burning down De Lacey's cottage—all's fair in revenge and war.
Quote 14
I had admired the perfect forms of my cottagers—their grace, beauty, and delicate complexions; but how was I terrified when I viewed myself in a transparent pool! At first I started back, unable to believe that it was indeed I who was reflected in the mirror; and when I became fully convinced that I was in reality the monster that I am, I was filled with the bitterest sensations of despondence and mortification. Alas! I did not yet entirely know the fatal effects of this miserable deformity. (12.13)
Aw. The monster is totally the unloved middle sibling. We feel you, monster.
Quote 15
My thoughts now became more active, and I longed to discover the motives and feelings of these lovely creatures; I was inquisitive to know why Felix appeared so miserable and Agatha so sad. I thought (foolish wretch!) that it might be in my power to restore happiness to these deserving people. When I slept or was absent, the forms of the venerable blind father, the gentle Agatha, and the excellent Felix flitted before me. I looked upon them as superior beings who would be the arbiters of my future destiny. I formed in my imagination a thousand pictures of presenting myself to them, and their reception of me. I imagined that they would be disgusted, until, by my gentle demeanour and conciliating words, I should first win their favour and afterwards their love. (12.17)
The monster’s desire for love and familial affection makes him a deeply human and sympathetic character. Yet it also drives him to commit his immoral acts.