Note: if I have been ninja'd, please inform me, I'm too lazy to check.
It's perfectly natural, what we're seeing isn't a fictional character; as far as your brain is concerned it's a representation of a real a real person. It possesses features you find attractive and all your brain notices are those traits that suggest a compatible partner to transfer your genetic code to.
It's no different than being attracted to a person in a photograph, pornography or even a painting of a real person; each of them are real people and you know this, but really they're representations of those people. A photo of someone isn't the actual person themselves, the fact that we can make this simultaneous link and distinction at the same time both consciously and subconsciously is a massive evolutionary advantage.
Cave-men knew this concept and there have been crude pornographic cave-paintings found in various sites across the globe; our ability to use these functional genetic traits in ways other than intended is what has given rise to creativity.
Essentially it's all based in our pattern-recognition ability where we are able to see faces in anything, we can tell which one of our species we'd most like to pair up with but also it would've saved our lives; it's a lot safer to be scared of a face that turns out to simply be some moss on a stone than to ignore an actual face of a very real threat.
So, no, it's not weird. Anyone who says they have never been attracted to a fictional character is lying. I'm sure they've imagined their perfect partner at some point and because of the traits they'd given to them would be attractive to them it's obvious that they're attracted to a fictional character because even though this person might exist out there somewhere, they don't know that for sure. Thus, since they created them in their own mind, a fictional character they will remain.