What is it?: Villains who got away with minor repercussions compared to their atrocities, just because of a bad childhood hastily tacked at the end due to them being fan/author favorites
Worst offenders: Nakago from Fushigi Yuugi, who despite doing nasty things for most of the story got a pass to heaven because he got abused as a kid...and excuse that was never implied before and only got hastily tacked at the end because the author grew attached to him
Notable exceptions: Animes where the villains gets properly punished (there's actually a lot, but I can't name any right now)
What makes it popular: Let's admit it, villains usually gets the bombastic dialogues, more cool-looking weapons, and leather pants. It's no surprise that fans and authors might like them more and more, leading to pressures to arrange a story-end that gives them happy endings.
It's not always bad, per se, but when villains that had done extremely nasty things get this treatment...f_ck!
Reason that I hate it: It's incredibly
unfair to their victims. Moreso when the protagonists ignored that the villain massacred millions of civilians just because the millions have no names - a statistic.
Is the hate really worth it?: YES!
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What is it?: Wimpy protagonists with no initial compentence that only got into the conflict, and become awesome, because of meeting mysterious waifs/encounter with ancient artifacts/jumped into a fancy mech/etc (in short, because the plot says so!)
Worst offenders: The majority of shounen action stories, though the freshest in mind is Guilty Crown which ironically is being broadcasted in the noitaminA timeslot, usually reserved for audiences lying outside of typical anime-watching demographics (i.e.
not shounen). Many Gundam and Macross "unwitting hero jumped into the cockpit" stories are also guilty for this
Notable exceptions: Full Metal Panic. The Lambda Driver is undoubtedly unique and mysterious, but Sousuke was already a competent mech operator and veteran soldier before getting the Arbalest
What makes it popular: Wish fulfillment. Most viewers are normal people themselves, so this set up allows them to dream that they too can be part of an epic story despite being "normal"...as soon as destiny calls
Reason that I hate it: It was fresh when Star Wars brought it to the big screen, but after countless similar set-up it gets really stale.
Is the hate really worth it?: For me, yes. Professionally trained heroes can be interesting too, you know. And why must heroes always depend on some fancy artifact or prophecy just to prove that they can be awesome?