Quote 4
I was dependent on none and related to none. The path of my departure was free, and there was none to lament my annihilation. My person was hideous and my stature gigantic. What did this mean? Who was I? What was I? Whence did I come? What was my destination? These questions continually recurred, but I was unable to solve them. (15.5)
You and us both, monster.
Quote 5
Sometimes I allowed my thoughts, unchecked by reason, to ramble in the fields of Paradise, and dared to fancy amiable and lovely creatures sympathizing with my feelings and cheering my gloom; their angelic countenances breathed smiles of consolation. But it was all a dream; no Eve soothed my sorrows nor shared my thoughts; I was alone. I remembered Adam's supplication to his Creator. But where was mine? He had abandoned me, and in the bitterness of my heart I cursed him. (15.11)
The monster may have learned a lot about making fire, but all he knows about human society he's gotten from books. This is kind of like watching a bunch of romantic comedies and then being sad because you keep passing by that cute bakery without running into a quirkily adorable girl.
Quote 6
"As I fixed my eyes on the child, I saw something glittering on his breast. I took it; it was a portrait of a most lovely woman. In spite of my malignity, it softened and attracted me. For a few moments I gazed with delight on her dark eyes, fringed by deep lashes, and her lovely lips; but presently my rage returned; I remembered that I was forever deprived of the delights that such beautiful creatures could bestow and that she whose resemblance I contemplated would, in regarding me, have changed that air of divine benignity to one expressive of disgust and affright. (16.32)
The monster is upset that normal people will not treat him with kindness merely because he is not attractive.