@Suiseiseki: Stoic, enigmatic, killing machine protagonists...

Suiseiseki
2011-03-17T06:08:29-04:00

Stoic, enigmatic, killing machine protagonists frequently get a polar opposite fan personality. I hardly even think anything of it anymore. The only reason it's remotely a spoiler here is because it's canon, and even then it doesn't really give away any plot elements.

Madoka is a magical girl

could be considered a spoiler at this point since you don't see it until so late in the series. Is Madoka is still NOT a magical girl a spoiler? That's something that's obvious in the beginning but one would expect it to change.

The underlying problem is that what constitutes a spoiler and why varies as it is a subjective concept. I personally don't find most spoilers very spoilery, as most of them require the context, the "why".

Homura used to be a nerdy girl

doesn't seem to spoil anything to me. If anything it adds another layer of interest. Why the change? What provoked it? Though I suppose I could see why some people wouldn't want to know about it, just when I first saw it I didn't get that "Oh wow!" moment, that moment where things in your head snap and suddenly everything is different.
Homura used to be a nerdy girl until she realized she couldn't depend on anybody but herself to save Madoka from her fate of becoming a witch that would destroy the world or dying in the process is a spoiler. The details here give away large plot elements.
Homura became a badass after having to mercy kill Madoka in an alternate timeline is a spoiler. And I'd say it's a spoiler of the worst kind, as it gives away one of the most heartwrenching scenes of the series so far, along with information that could easily allow someone to figure out other things and spoil themselves to everything.
Mami is an airhead is a spoiler (and a very cruel joke I might add.)

It just feels odd to nitpick what could effectively be an artist's whim just because it happens in the series. If Haruhi suddenly genderswapped Kyon and the plot was loosely based on the Kyonko fan character's exploits are those now spoilers?