considering he never did anything really evil. He did make the experience at the Academy unpleasant for the Baudelaire's. But he never joined Olaf. He never killed anyone or started a fire. Besides being rude, selfish, and incredibly annoying. Would you consider him a Villain or Volunteer?
Such a hard question! I'd say he's too stupid and delusional to know what's going around him thus doesn't get involved in either side.
Well, he sure isn't a volunteer. But he does leave glasses on polished wood without using a coaster, leaving an unsightly ring. That says "villain" in my book. ...But in all seriousness I think he has no idea of the complexity and mystery of the situation he's in, and probably doesn't care, either.
In TBL Lemony says "I will love you until N realizes he is unworthy of the V" or something to that sort, which obviously means Lemony knew him in the past along with all the other VFD members mentioned there. Also he was at Hotel Denouement which could mean he was there for the VFD gathering or whatever it was (I've forgotten) so i think that he does have something to do with it all, which side he's on though, I can't say
Nero does not seem to do anything villainous except playing the violin when he cannot (which can be quite villainous), but he is very self-centered and just treats everyone the same. For example, he thought that sunny was a concierge but still mimicked her. Anyway, he only went to hotel denoument because he thought he was going for a violin recital of some sort and finally could show off the talent he did not have.So he's neither.