In one story of mine, the protagonist is a physically disabled teenage hacker with no knowledge of the supernatural, who gets approached by a child vampire looking for help finding pedophiles to bite. I'm really struggling with one thing - how this kid (and his mother, who is in on it all) accepts that vampires exist. He starts out deciding that he dreamt this vampire up (the vampire visited at night, when he was half-asleep). This falls through when his mother sees the vampire too. Then they fall upon the theory that the guy is a government agent with weird enhancements. But gradually they'll start realizing that he's way too old (2,000 years old), has no affiliation with the government, and some things he can do are very hard to explain with modern technology. I'm worried because most books that have a person discovering the supernatural have them accepting it way too easily. So I want to make sure it's a more realistic adjustment. It'll be hard because this kid is a real sciencey guy, and a lot more ready to believe in conspiracy theories and such than in actual supernatural stuff. (He's going to end up realizing that magic doesn't contradict science, it's just another law of nature.) But he will eventually figure out, since at some point he's going to become a vampire himself.
If your protagonist’s nature is one that will not let him easily believe in the supernatural, then set in motion a chain of events that will gradually convince him. Wear down his resistance, if you will. You’ve got a great start. First he sees it in his room, thinks it must be his imagination. Okay, now mom sees it as well so he knows it’s not his imagination. They think it’s some government agent, but then realize there is more to their conclusion than meets the eye. I think you just need to continue along this vein. Maybe he sees things that make him suspicious, or something happens to him physically. Perhaps his mother is the first to realize the truth and tries to convince him, etc. Keep going until your character is faced with the inevitable truth. If the reader sees your mc gradually changing through these events it’s likely that it will become believable to them. Hope that helps.
You could do it the slow way, with plenty of smaller incidents but don't forget the 'baptism of fire' route. One huge incident that convinces him beyond belief. It might seem like its a really hard thing to write, and it is, but honestly its a hell of a way to get your character believing without spending time dreaming up many encounters. Either way your idea sounds awesome but just thought I'd give you something to think about
I have a quick question, why would the guy and his mom think that a child is a government agent? Pedophiles are attracted to prepubescent children, so in my mind I am seeing a kid around 11 or younger. As far as bringing someone around to accept the supernatural, I think the others are right. Creating situations that shows them irrefutable proof that he is supernatural, leading up to one big unveiling, is a good way to go about it. At the same time, if he thinks that it is possible for science to manipulate someone into having vampire-like qualities, there may always be a seed of doubt in the back of his mind, even once he gets to the point of helping the vampire out. Just another thought.
What everyone has said so far is great. Personally I've gone the opposite rout facing a similar situation as my chararacter is introduced to magic and so forth. However since his personality is an easy going one, it takes only a chapter and a half (as well as a pretty exreme event) to get him to believe in it all, and then want to know more about it.
