A general desire for information. I first really started in 1st grade looking up pictures of license plates (my opa collects them and I wanted to as well) so I'd go through license plate collector portals and download all the images I could. When Diablo came out I then downloaded tons of animated gifs of moving enemies and blood drips and pentagrams and stuff, also portal-whoring. Loved Geocities/Lycos/Angelfire/etc sites and their image-heavy layouts.
I didn't get into discussion stuff until about 4th grade, and was pretty light about it then, mostly posting on guestbooks of Digimon fansites and stuff. Around the same time I took my first step into piracy with SNES ROMs. However, I still did things aside from the internet back then, like bike riding and exploration and building hideouts and stuff. It was expulsion from school in 6th grade that drove me into a full-time e-life, although tbh I had already gotten big into Rotten and Ogrish and shit even before expulsion. Since then, it's been the internet community that provided my only outlet for social interaction.
EDIT: Oh yeah, IRC was good fun too. Started that a tiny bit later, more around 7th grade though. I've tried getting back into chatrooms but my mental health has decayed since then and I've forgotten how to use them.