It’s like Grace when she grew up to be 12 years old and given to a Swedish family. Eli and Oskar, though children, fell in love in a hopeless place — literally. Eli, though a vampire, was surrounded by love; love from her “father,” which was a selfless kind — he compromised his morals and sacrificed his life just to be able to feed her. The movie gives a twisted kind of meaning to the whole idea of love and life, a warped understanding of what it really means. How pure is love, if it’s for something that may be essentially wrong (someone’s life for another).
The two ended up complementary to each other. Oskar needed someone to make him a stronger person, which he found in Eli. Eli needed someone to simply accept her without being under nor above her; she needed to somehow have a connection to the human world and a reason to live. I say this because the woman who died (as she was becoming a vampire) was so afraid to fully transform because being a vampire is like death — you have no friends, it will eventually ruin your life. Knowing that, she asked her husband to kill her, to euthanize her. Since he didn’t do it, she planned her suicide by sunlight. Eli would eventually come to this, with no friends and no family. It would have been inevitable.
The whole idea of vampires was just confirmed by everything that Eli was. She would burn in the sun, she can’t come into places without being allowed in, she can fly and has super strength, and last but not the least, she has a weakness for human blood and only human blood. Again, the very idea of a female being the monster is in itself a patriarchal idea that stems from the understanding of women as the “other,” the “object.” Eli as the monster was still — despite the monster characteristics — the woman.
Interestingly, the movie can be interpreted the other way around. Gender roles can be seen differently in a sense that the monster, the strongest character in a horror movie, is always manly. When Oskar was the “damsel in distress” and Eli was the only hero to save him, it was obvious that Eli was the “male.” It’s fascinating how this played out, because the ideas of sexuality were overflowing in this movie, from the innocent-ish bedroom scene (where Eli was basically the more aggressive one) to the killing-bullies scene. Oskar ended up taking care of Eli in a sort of womanly way, because as the human in the relationship he had to make sure that her needs were accommodated. Girl power!