Is reddit not forum-y enough? There are "posts" which are sort of akin to threads and people reply with comments on that parent post. And there are subreddits for practically every subject under the sun. :o (Although 9/10 times I feel like the average "redditor" attitude is fairly insufferable haha
)
As far as other virtual pet/weeb subculture things along the same vein of Neopets, Subeta might still be kicking and is very much more adult oriented. Likewise if you like dragons Flight Rising is supposedly quite popular but I can't attest to the generality of forums available there or if it's really just all dragons. xD I do miss Gaia in its heyday because as a forum is was extremely bumpin, but basically dead these days.