Why couldn't the Creature, in Mary Shelley's Frankenstein, fully sympathize with the characters in Milton's book?
In chapter fifteen of Mary Shelley's novel Frankenstein, the Creature gives his account (through Victor and Walton--given this is a multiple narrative perspective) of his life. It is here where the Creature details the reading of three novels: Paradise Lost, Plutarch's Lives, and Sorrows of Werter. According to the Creature, while all novels provided new knowledge, it was Milton's Paradise Lost which proved most intriguing for him. The two "characters" brought up in the novel are Adam and Satan. While the Creature can relate to both, other aspects of each alienate him (the Creature) from them as well.
First, he recognizes that Adam is unlike any other creature on the face of the earth. In this sense, the Creature can relate to him. On the other hand, Adam "had come forth from the hands of God a perfect creature, happy and prosperous, guarded by the especial care of his Creator." Therefore, unlike Adam, the Creature is not perfect, happy, prosperous, or guarded by his creator.
Second, he recognizes the fact that Satan has been exiled by his creator. Envious of the love God had for those he embraced, both Satan and the Creature fell short of the love of their creator. That said, the Creature was still unlike Satan. According to the Creature, "Satan had his companions, fellow-devils, to admire and encourage him; but I am solitary and abhorred." Therefore, unlike Satan, the Creature had no one at all.