I was maaaaybe 12 when I first got into online HP fandom, because that was 1999-2000 and that's when the Unofficial Harry Potter Fan Club was active <3. We had internet at my primary school but not at home and I would go online during lunch breaks and read terrible, terrible fic. It was so bad. Soooo bad. I mean, I knew it at the time even, but it was what we had. That and writing it amongst my friends. Then FF.net started up and oh, the wonder and glory. And if anyone's boggled by the fact that I was reading that stuff at 12, my little sister was eight when she was reading Sailor Moon fic on FF.net. With my mum reading over her shoulder!