A good antagonist should be identifiable with in some small way. Not only are audiences bored with a standard "good versus evil" plot, but an opponent with ideals is more appealing than one just trying to take over the world. Magneto is a great example. He's a guy just trying to take care of mutants, even though his methods are sometimes morally wrong. On the opposite side of this are the X-Men, who are also trying to take care of mutants, but through reconciliation and cooperation with humans instead of violence and subjugation. Or in the recent Dawn of the Planet of Apes, Dreyfus and Koba are faced with considerable threats, and decide to respond with preemptive violence. Are these characters in the wrong? Sure, but we can understand where they're coming from. If you knew that a group of people was building/creating/amassing weapons for the sake of wiping you and everyone you love off the face of the planet, would you be able to resist the urge to attack them first, before they could harm the ones you care about? You start out knowing or the movie manipulates you into thinking that Magneto is a supervillian, so he must be wrong, or Monkey With a Scary Face must be wrong, but at some level, we should be able to understand what motivates these characters' actions and hopefully empathize with them, even just a little bit.
Moreover, struggle between these characters should represent a larger struggle between ideals. When you see Magneto and the X-Men fight, the question is not "Which mutant is stronger?" but "Which belief (do the writers think) is right?" It doesn't matter if Neo or Agent Smith is a better fighter, what matters is the ideals they are replacing during a fight scene. Darth Vader has years and years of experience wielding the force and fighting, but in the Star Wars universe, good triumphs over evil, so he will lose the fight to Luke, who had days and days of experience lifting muppets.
With that in mind, what's up with Loki in this movie?
We know the ideal that Loki is presenting. We know this very well, because hack writer Joss Whedon presents it to the audience in the form of an expository speech that Loki gives in front of a bunch of German citizens: People want to be dominated by a ruler. Isn't Loki's goal to conquer the whole world? Is he going to give this speech every single time he runs into a group of people? Why is he explaining his motivation to what he believes to be his inferiors? Oh right, because writing is hard, you guys. It's so much easier to just have Loki tell you everything, instead of showing it to you.
For starters, you already know how I feel about him just explaining this shit to the audience, when a much better method would be for him to wreck havoc in Germany, and threaten people to turn against each other, their families and their nation for the benefit of being protected by him. What really hurts about this scene in Germany is that it starts out on the right track: Loki does some scary shit, people get worried and bow out of fear. It would have made sense to take this a bit further and have Loki tell them to, I don't know, fight each other for the honor of being able to serve Loki in safety. Or if you destroy a German government building, Loki won't hurt you. Have the people actually choose sides for their own selfish sakes.
But, that's still not that good, because Loki is positing an ideal that nobody actually believes. You hear "Human beings want to be slaves" and you can't think of anything that makes less sense than that. Even crazy dictators didn't believe shit like that. Even in my "Show Don't Tell" example just now, that's presenting more of a "people seek protection above everything else" belief. So, of course, an old guy in the crowd says, "No, we don't want to be subjugated. That's fucking dumb," because it is.
This is completely ignoring the fact that I can't understand why Loki wants to conquer Earth anyway. As you may recall, this movie has a problem with consistency across the other movies in the Marvel universe. (Seriously, Joss, all you had to do was watch the other movies a few times, then you might understand the characters you were writing. This shit is not hard. I know you have Netflix.) So out of the 7 or 9 or whatever planes of existence that are known to Loki, one of which includes a realm that is rightfully his, and one of which is a magical land of godlike beings with advanced scientific technology, that if you recall from the first Thor movie is exactly the place that Loki wants to rule, Loki decides to spend his time conquering Earth. Why? Because falafels are delicious. (HA! That's so random, am I right? Falafels! You guys, I'm a funny writer like Joss Whedon.)
But ok, the studio says that Loki has to be in the movie because he's the biggest draw, and the movie has to be set on Earth so we can get the other heroes involved. Fine. How about we give Loki the kind of motivation that a real person might have, instead this elementary school level antagonism of "Let's rool the world because people would like it."
Try this on for size: Loki comes to Earth, but instead of landing in Germany for a contrived reference to Hitler, Loki and his staff land in the Middle East, in the middle of a firefight between two armed groups in a residential area. Because we don't need to get too political here, they can just be identity-less fighters, endangering the lives of the civilians around them. Loki shakes his head and comments to himself how even though these inferior beings (humans) are part of the same realm (Midgard), yet they fight amongst themselves as if there was an actual difference between them. He then uses his mind control and deceptive powers to turn the militants on themselves, and soon they incapacitate the members of their own group. The civilians begin to notice that the fighting has stopped and notice this lone man standing in the middle of it all. They rightfully assume that he has ended the fighting and began praising and thanking him for it. Loki looks disgusted. "Bow," he demands, and as the civilians look confused at this command, the Earth begins to shatter and split open. Every innocent person falls into a pit where they are set upon by demons and monsters. It's a terrifying scene that continues just long enough for the horror of it to sink in, and then suddenly, everyone is back where they were, in front of Loki, realizing that the torment they just suffered through was entirely in their minds, and with the power of his staff, Loki can turn that on or off as he wishes. One by one they bow to him.
Reasons why this is better than Loki reading the fucking script in fucking Germany:
One - Loki's ideals may be arguably good or bad, but his methods are extreme. What Loki is advocating in this scenario is safety in exchange for subservience. We get to see that these people's lives are in very real danger in an event that actually happens around the world every day, and Loki changes that. Under Loki's system, there would be no fighting and there would be no needless killing, because we would all be under his sole reign.
Two - This establishes Loki has a credible and terrifying threat. One the oft-quoted lines from this movie is the "He has an army." "We have a Hulk." bullshit. What I hear from this line, and why it is so toxic to making a good movie, is this: There is a problem that needs strength to be solved, but there is absolutely no reason to worry, because we have the strongest thing in the world. This dissolves any possible tension the fight could have had, while presenting an obstacle that nobody needs to grow or change to overcome. Hulk starts out the movie punching things, and ends the movie punching things. But a movie where the threat is not in Loki's physical might, but in his ability to deceive his opponents is a conflict with unclear outcomes. After all, you have a bunch of strong people put in a situation where they can't punch their way to victory. They have to learn shit. They have to think outside the box to defeat Loki's mind games.
Three - Remember when I said that good fights should present two ideals, and the one that the writer thinks is stronger will win? If Loki presents an ideal of ruling through fear, The Avengers may be able to represent an ideal of protection through collaborative effort. (Get it? That shit is a metaphor for world peace, ya'll.) I suggested before that instead of the movie being about fucking nothing, the movie could be about Captain America bringing the team of Avengers together and learning how to lead them. We could show Cap wanting to protect people from Loki's fear tactics, but being unable to do so on his own. He has to learn not to control and manage the other superheroes, but work with them and convince them to act together as a team. Remember in the end of The Avengers where all them are fighting aliens, but they're all doing it separately and not at all together? (Except for the one scene where they stand around and pose, of course.) Instead of the climax being "Get one guy to fly a nuke into a spaceship" we could show that individually we are weak, but we can work together for the greater good.
Part of a series on The Avengers:
Part One - Bias
Part Two - Main Characters
Part Three - Consistency
Part Four - 8-Bit