Pedophilia... for a fic, not art, involving a chibi form. (Is the chibi form canon?) Gaah.
I try to warn for everything. I prefer the "white on white" warnings, so that people who don't want to be "spoiled" can avoid them, and those who are susceptible to squick can skip the stories they don't want to see. (I don't read warnings at all, if I can avoid it--I want to know how many words the story is, and overall tone, and that's about it; I don't need to know pairing or even fandom with a good rec.)
But there are some cases where I honestly don't know how to warn. I wrote a short crackficcy thing, about using a pensieve for swapping pornish memories; it implied that half the teachers at Hogwarts had been doing bizarre and rude things with creatures of various levels of sentience. I didn't know if I should warn for "implied bestiality" (is Hagrid/Fang a "chan" situation, since Fang is under 16?), or if the implication was vague enough that I should just warn for "squicky history involved."
Some chan is easy to identify, easy to warn for. "Snape seduces 14-year-old Harry"... no problem. However, Ron & Hermione during the year they're on the run? They're of legal age in their country. During the month or two when one of them's 18 and one's not, is that a "chan" warning? If Snape doesn't seduce Harry, but thinks about it, and decides he'll wait until Harry's 18, but lusts after him until then... is that "chan?"
(Or "shota." Is there a difference?)
I want to give appropriate warnings. However, as a fan of "squick-heavy" fic, I don't want to over-warn... I'm annoyed when I spend time reading a 12,000 word fic that claimed "dubcon chan," and find out what it meant was "a couple of kisses that a 16-year-old wasn't quite ready for." Just like I'm annoyed when I click on "NC-17" art... and find out it's Snape holding a fully-clothed, bleeding-profusely Harry in his arms. Not even gory details, just a hole in his robes near his heart, and a pool of blood.
"Character death" is not "NC-17." "Slash" is not "mature themes;" a male/male kiss is no more intense than a mixed gender one. "Teen lust" is not "chan." (Teen sex may-or-may-not be.)
I like warnings; I just want to know what they mean. And in this archive, crossing many fandoms, I'd really like some idea what to expect.
I expect there's always going to be a problem with over-warning; some people think anything more intense than ET is an R rating. But it'll help if there's no penalty for "low" ratings, and some clear guidelines for the differences between the warnings.