The Mummy, the Will and the Crypt by John Bellairs.
Okay this kid, John Dixon, is shy with pale skin and freckles. He doesn't really have any friends his age and he hangs around with this old man, a Professor, which for him is actually a step forward socially because most of his free time is spent reading books alone.
That was me as a kid, pretty much. My parents had to pull me away from books to go play with the other kids in the neighborhood. In fact, I specifically remember an afternoon in fourth grade, curled up with this book when a girl from down the street came knocking and I had to chose whether to keep reading or go outside and play.
Anyway in reading about this book as an adult I can see the attraction. I've always liked being scared - anything on the edge has an instant attraction for me, and I've always liked searching for answers to questions. He's searching for clues to a mystery and finding those answers empowers him - gives him the ability to rise above his little geek bubble the same way the book helped me escape mine - or at least forget about it for a little while.