I think it would have probably have been .Hack//AI Buster I was pretty young at the time and was just being introduced to the internet and the world of games. So a whole open world game where you could live an entirely different life was really enticing for me and I've been obsessed about .Hack ever since.
The first book with which I ever completely fell in love was Piers Anthony.
Wait--I mean Xanth. No! I meant A Spell for Chameleon by Piers Anthony.
Directly after reading A Spell for Chameleon, I read The Source of Magic. Then I read as much of the Xanth series as existed at the time. Then I read all of the Apprentice Adept series, and then the Incarnations of Immortality series. Then I found out that Piers Anthony had written a bunch of science fiction novels, and read those in the order of which I could find them at libraries. I was around the age of eleven, and it took me a few years to get through it all. In retrospect, I wish I hadn't devoured them quite so intently because now a part of myself believes that it grew up in a magical pun-derful land. I still re-read a few of the Xanth novels every year or so.
I had a deep problem and still do about obsessing about Harry Potter. It is too the points where i am writing a harry potter fanfic for nanowrimo
Harry Potter... when I was like 6. Actually, I don't think that was the very first book I was obsessed with. I became in love with a couple of series around the same time. I use to LOVE Nany Drew and this Treehouse book series. I forget exactly what it was called but it had a brother and a sister who went on magical adventures in their treehouse or something. And Junie B Jones, I loved that one for a little while. I also loved a Series of Unfortunate Events (and still do!) when I was a bit older, probably around 10.
MAGIC TREEHOUSE!!!! I LOVED those books! I swear, most of my random bits of history trivia come from that book series!
Hmmmmm..... My first book obsession..... was probably the Young Wizards series by Diane Duane. I had liked Harry Potter (a lot) but the YW series seemed a lot better to me. Still does, in a lot of ways.
I liked the YW, but I felt it fell off after about 5 books...
Obsessed? Well, I'd have to think on that one. I liked the Harry Potter series, but I'm not sure I was obsessed with it. I mean, I read them at age 5-8. I can't really remember. But I do know I was obsessed with the Percy Jackson series. Nowadays, I'm obsessed with the Hunger Games, the Inheritance cycle, and (still) Percy Jackson.
i made the mistake of reading a couple of her later books...now i'm torn about backtracking.
I absolutely adore everything by Mercedes Lackey.
I started with the Last Herald-Mage trilogy, and then went on to discover a collaboration novel with Piers Anthony. After that, I just read everything of Lackey's I could find.