People love heroes, obviously, but what if that hero were a monster? In my sci-fi story, I thought of taking a Devonian (not Kenthew) and painting him up to be a sympathetic, heartfelt, brave warrior who wants to help his people from the Altran slave owners. He's essentially the leader of the Devonian Resistance. Pretty swell guy, right? Well, I think after I establish that, I reveal he's really a brute who shows no mercy to any Altrans he and his group meet. He even takes Helen prisoner when she makes it clear she won't stand for his atrocities, believing her an Altran sympathizer. He has his reasons of why he's doing this, but I'm wondering: How would readers feel about this? That the person they were rooting for was actually a monster? Would they throw the book down and not read it? Keep going? Would their reaction depend on what this guy did (and will do to poor Helen when he takes her captive?) I just want to gauge it.
If you do it right, people will love the character. This is the rare but classic "antihero". Examples include The Punisher, Megamind, any character portrayed by Clint Eastwood, Han Solo, Jack Sparrow, Noah Bennet from heroes, Mal from Firefly. What all these characters have in common is that despite how despicable they are, they have qualities that overshadow their weaknesses. Megamind is in love, Noah Bennet does all the horrible things to protect his daughter, and Mal is above all altruistic and honest. Be careful, though, if it comes too late and is too big of a surprise, the readers will be turned off. If you are doing a "surprise! He's a monster!", build up to it so that even if the readers don't expect it, they understand it and it makes sense given the way you depicted the character earlier. Maybe a few temper outbursts, or the way other people talk about him. It just can't be a huge drastic in-your-face turn around.
By the fact you're asking this, and focusing on a 'reveal', it sounds like you're wanting to play a trick on the reader. Bad idea. The better idea is to just write from the perspective of a character who is complex and as often happens in life makes mistakes, does bad things, but has reasons and motivations that even if the reader doesn't like it, they can at least empathize with the character. Doing this isn't playing a trick on the reader, it's just writing good fiction.
I also think that it would be great if something extremely traumatic happens so he turns even more in to a monster. Kind of like when Anakin Skywalker finds out that his mother was killed by the tusken raiders. But make it more believable and cooler than that, it wont be hard.
This is the crucial part. What are his reasons? You can create the most repugnant character in the world, but if the reader can sympathise with him then they will follow him on his adventure. Sympathy is the key. I personally would stop reading if the character I thought was a hero suddenly starts commiting atrocities based solely on a hunger for power or some other inexcusably evil motivation. You can make your readers hate a main character's actions, but never the character. Always retain that fibre of humanity that plays at the heart of the audience. Think Anikan in Episode 3. His transition to the dark side was riddled with the slaughtering of many innocent people, but we stayed with him because we sympathised with him. His actions were driven by his love for Padma and the fear of losing her, and not malice.
I would personally say, especially with a character such as this, that empathy, not sympathy, is the key.
Not necessarily. In this case you would want to evoke both. It's simply a matter of semantics. It's the difference between feeling sorry for them(sympathy) and feeling the sadness/loss they feel(empathy). Either way you're feeling something other than hatred for the villain. It's really just a technicality which of the two is key, but the point is the same.
In fiction, from a narrative design standpoint, the difference is huge. As you point out, sympathy relies on feeling sorry for the character (though that's more an emotional description, in narrative design a sympathetic character is more one the reader can feel for, whether it's liking them or thinking they're hot). Sympathy relies on presenting a likable enough character that it can overcome the narrative distance between the reader and said character. It's why 'hero' protagonists are often successfully employed in omni or other distant, non-limited POVs. Empathy relies not on presenting a likable character, or even one you feel sorry for, but one the reader can understand. Even when you don't like what they're doing, you still understand why they're doing it, how they feel, what their motivation is, and on a direct, experiential level. It's a much stronger tie that isn't broken, like many sympathetic characters, when they then do something you don't like. The biggest differences is that instead of having to add in little gimmicks that get the reader to 'like' the character or excuse their actions, you can just deliver the truth of that character's experiences, and it's enough to keep a reader reading. We see these little gimmicks litter movies (even good ones) and bad fiction, because it's relying heavily on a surface experience. You end up with the (usually ridiculously poorly written) moments in movies where we're presented a 'bad guy' or 'good guy gone bad' and given the 'bad guys killed their family' moment where the character balls their fists and yells 'NOOooooOOOOOoooooOOOOO' and we're supposed to then think 'eh, okay, I guess it's okay he's bad or gonna do bad things.' In fiction we can, thankfully, go deeper than that. We don't need gimmicks to raise sympathy levels like it's some video game. With empathetic writing, putting the reader firmly IN the experiences (external and internal) of the character, we'll connect the reader even if there isn't a single shred of like or sympathy for that character. Of course, there are plenty of successful books (in terms of sales, at least) that rely purely on sympathetic narration styles and are full of these gimmicks (because they have to be). Doesn't mean they're always good or well written or the best source material to learn from, though. (and I know, I know, it's all subjective and 'good' is simply what each of us values as individuals, etc /eyerollingfont) But really, citing Star Wars and Anikan's change to the dark side? That was some of the most poorly written/directed/acted crap I've ever seen, and if that kind of junk was in a writers first manuscript they were sending to agents it would be shunned and laughed at. I'm a huge fan of Star Wars, but that was NOT good writing, even for a movie, but especially for an example to use to inform one's fiction, and excusing/defending/citing bad writing just because it's popular or someone famous can get away with it isn't the best material with which to build your house (us all being pigs, and the publishing world itself being the big bad wolf... which means we're actually trying to break into the big bad wolf's house to find success, or perhaps just hoping we even survive).
By the time there is a tone change, you will have wrote this so well the readers are hooked like lab rats, they will react by reading on (of course). Quit worrying about what others think! Link I suggest you buy the Allman Brother's "Eat A Peach" the cd will wash the rust belt liberal out of your mind as your embrace your southern heritage.. Do you think Marget Micthell cared what the bed wetting liberals thought when she wrote "Gone With The Wind" while living on Peachtree street?
Okay sorry I cited Star Wars. It's probably one of the most famous examples of a main character's transition from good to evil. And just because you dislike the way it was directed/ acted/ scripted doesn't mean it can't illustrate how the average viewer felt sympathy/empathy for the character all the way through his descent into darkness. I'm sure many people agree with your opinion of the movie (and many would disagree), but the fact remains it still demonstrates the point. Most people( by that I mean the world, not some rarefied intellectual with a writing degree) did feel sympathetic towards the character, so I'm not sure why you suddenly turned the end of your post into an acerbic criticism on my example. As for the rest of your post. I agree. I still think it's very technical. But what you're saying is technically sound. When you go that deep into the significance of the words then sympathy falls one layer short of empathy, and it is empathy that you should be aiming for. But the overall point remains. Don't alienate the main character from the reader by turning him villainous without the proper motivation. You must not sever the emotional attachment between the audience and the character.
Yes, we do agree. People are complex and don't just 'transition from good to evil' like in [personally, subjectively bad] stories. To get characters to be believable and feel authentic, you can't just have them 'transition from good to evil' as, at best, you're then going to have to rely on a state of suspended disbelief boarding on hoping your audience has been drugged dumb with it. Sure, writers get away with it, but that doesn't mean it's good and doesn't mean an aspiring writer will get away with it. The better strategy is to build a complex character that is both good and evil (as most of us are), because really only a two-dimensional character can transition from good to evil, and such characters are not usually very compelling, rely on sympathy almost exclusively, and in the end are easy for a reader to dismiss. Building such a complex character requires a bit deeper levels of character introspection, and more of a connection between character and reader to keep that reader from turning away when things get ugly. I've found that when you start digging into an empathetic approach, the sympathetic becomes so secondary it doesn't even matter anymore. You don't have to worry about explaining or justifying a character's motivation (often how it is required for a sympathetic character), because that motivation is simply there, in the experiences of the character, and understood by the reader. I think people put too much stock in sympathetic characters/stories/subjects/etc. I think most readers, across all genres and styles, are more captivated by a study of the human condition. Whether it's a deep, highly philosophized, introspective study, or a more surface one focusing on things like events and plot points, it still has to ring true, and still has to keep the reader engaged. There are certainly segments of readers that form genre expectations, and with those expectations come allowances certain readers of certain genres will make (like comic book hero genres of writing allow for somewhat two dimensional characters, but even that is changing and more authentic complexity is expected these days). I don't personally believe in writing, or advising writers, to shoot for being the exception, though.