What is Håkan's background?

Since the beginning of Let the Right One In (orig.: Låt den rätte komma in), Eli was accompanied by Håkan, an older man, who tried (not very successfully, though) to kill people and gather their blood in order for Eli to not have to kill anyone, it seems. And when Eli visits him in the hospital (after he failed to kill another one and disfigured himself to prevent her being discovered) he finally sacrifices himself to Eli as blood source.

But I'm not sure what to make of his character. What was his relation to Eli and why did he help her, up to the point of sacrificing himself? While she said he was her father in the hospital, this doesn't really seem to match her relationship to him as depicted in the movie and to me seemed more like a cover-up just told to the nurse (but I might also be wrong with this evaluation).

Best Answer

My impression from the film was that Eli had met up with Håkan when he was still a child, the same way she did Oskar, and that he grew old while she did not. It is never stated explicitly, but it isn't contradicted either.

However, the novel on which the film is based does give additional background for Håkan. According to the IMDB FAQ:

Håkan (Per Ragnar) was Eli's "helper," meeting Eli at a low point in his life when he is contemplating suicide because of his liking for young boys. Eli recognises that his vulnerability and exploits this, using him as her source for food.

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Håkan truly believes he loves Eli, but his infatuation (a more accurate description) is largely motivated by sexual attraction to Eli's childlike body;

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Eli found Håkan when he was about 45 years old.