People email me a lot and ask if it makes them a bad person if they like fictional villains.
I think the answer is: no, of course not, it doesn’t make you a bad person if you like fictional villains. 99.9% of people consuming media know that fiction is fiction, and they don’t apply the rules they would apply in real life to fictional characters. The other .01% have problems a lot bigger than fictional characters, their opinion of.
People like villains because villains move the narrative along. If there was no Loki, the Avengers would have no reason to assemble. If nothing much is happening, you can rely on the villain to show up and set off a bomb or threaten the universe, thus causing your heroes to have to do something.
You don’t have to apologize for villains, or find some way to explain how what they did isn’t so bad, to like them. You can be like, “Loki, he is a mass murderer, but if it were not for him and his planet-sized Daddy issues, there would be no Avengers movie, and then what would we make gifs of? Moriarty, also a homicidal maniac, but if not for him, Sherlock would never have discovered his humanity, because he would have no impetus to do so, so hey.” That is why the trailer for Into Darkness is narrated by the villain — because it immediately sets up stakes: something is happening, as opposed to having Kirk narrate by saying “Here we are in space, I love space!” Benedict Cumberbatch’s VO doesn’t tell you what’s happening, but it does tell you that something is happening: i.e. conflict (the gasoline that runs the engine of every narrative.)
Villains provide impetus and prevent stagnation; that is what we actually like about them. In real life, we have no need of villains to show up and provide impetus for everyone to do things, because in real life it, is okay if everyone is happy - in fact, preferable - but real life does not have to entertain bazillions of people.
Anyway. More specific questions about Sebastian under the cut; read more for spoilers for CoLS.