I just got done tearing up the series on the books board before seeing this so it gives me a chance to play Devil's Advocate, but I'll point out that just about none of the great classics, and EG is, actually have sound plots when you pick them apart, and as they expand into series people do that more. Most of the characters in them are pretty warped, especially the interesting ones.
Context, Speaker for the Dead is the real original book, Ender's Game is a prologue of it written as an expansion of a short story which had no revenge plot or beatings and killing at all. It's a duology and the entire point of it is very definitely NOT a revenge fantasy but the opposite, why revenge is almost always a bad idea. Also the point of 'Battle School' was to find someone who prospered because of the stresses, a unique freak who would continue to be a brilliant strategist as he faced progressively harder and more impossible battles because their fleet traveled at lgiht speed but they had instant comms, meaning their newest and strongest ships were arriving at the sparsely defended fringe worlds just as the oldest and weakest fleet was arriving at their homeworld. There's some plotholes there but its sound enough.
Well Ender is, incidentally, not actually supposed not be the hero of the book. He's regarded as such because he's the focus of the book so he benefits form that in reader's eyes. He is specifically supposed to be terribly depressed, borderline suicide, miserable neurotic wreck who is so victimized by every semblance of authority he's exposed to (a third child in world that regards them as taboo, a psychotic older brother, teachers who throw him to the wolves, etc) that his self-preservation instinct makes him turn to extreme overkill as his only perceived recourse, and that's he very good at it because he's very good at getting into other people's heads, but it drives him nuts and emotionally distant because he defeats his massively more powerful enemies by getting to really know them to learn their weaknesses and thus comes to like them a lot, but still murders them. He's not the hero, there are no heroes or villains in the book.
Again, the point of the book - and the movie fucks it all up - is that he does not consider himself guilt-free of the act, and nobody else does either, especially after he wrecks his own hero-status. Nobody in the follow-up book regard him as a tragic or besmirched hero nor does the book imply he is but others don't recognize it. They all regard him as an utter monster or at best a monster child seeking repentance and reform. The genocide as bad thing is the major theme. Now Card does go on to fuck that up in future books, but in the original 2 its ironclad, in the follow ups he manages to rewrite things so that the genocide is utterly appropriate in my opinion though this is clearly not Card's intent.
Not really a Mary Sue, except maybe for people who enjoy Angst. Definitely not a Revenge Fantasy, Death Wish and Dirty Harry are revenge fantasies, Ender's Game is not that.
Again that is rather the point, they are trying to find themselves a military genius who responds with crushing force and cleverness to an enemy that is much more powerful and can't be negotiated with. I don't personally by into emotionally abusing people to 'toughen them up' in the service, but most people even in the service take that as a truism so I won't blame Card for assuming so.
Card's been subject to a great deal of trumped up abuse in the press of late, not entirely unfairly but most good authors have fucked up views on something, either because most of us do or because you need to be outside the normal box to write a good original story or both. I've never gotten anything off hi writings other than that he's turned a bit irritable and crotchety in the last few years. Ender's supposed to be a really fucked up kid, caused by emotional and physical abuse, this isn't a recurring theme in his others books of which he has many. GRRM, great writer, has some seriously fucked up and traumatized major characters and explains how they got there in graphic detail, doesn't make him guilty of incest for having Jaime do it and write him up as a nice kid turned ruthless bastard turned redemption seeker, which is the same damn character as Ender.
I don't really think of it as a YA book except in the sense that any of the classics which aren't brutally adult, like aSoIaF, are best read early. It gets labeled YA mostly, I think, because the characters are young, smart, unpopular and thus interesting to young people who might feel they share those traits. It's not an incredibly deep book, mentally or emotionally, but it's a perfectly good adult book. I never thought of it as giving advice on morality beyond the direct: "If you get to know and understand your enemies you might find out they aren't bad after all" and the indirect: "Wallowing around in prolonged periods of guilt and self-loathing and removed into a fantasy world is really unhealthy" though you'd have to read Speaker too for that point to be driven home, they're twinned novels though, the second is not a sequel, EG's a prequel written after but published slightly before Speaker.
Anyway you're wrong about almost everything, though the movie sucked great big donkey balls.
- Albert Einstein
King of Cairhien 20-7-2
Chancellor of the Landsraad, Archduke of Is'Mod