(Note: I'm a little late, I'm sorry. This weekend has been a rough one.)
I think I read Neverwhere by Neil Gaiman when I was around 13 or 14. I'm not sure what had me picking it up (but thinking to that time period, my best friend then was really into Sandman and maybe she read this too and suggested it). I don't know. But it was my first Gaiman book and it started a lifelong love. He's on my instabuy list!