I know this may come as a surprise to a lot of you fangirls out there, but LOKI IS A BADGUY.
Yeah yeah, I get the whole misunderstood thing, how he's just lost and lonely and feels betrayed and unloved and all that nonsense. But the thing is, he's had plenty of chances to get his head out of his ass and realize that (a) his father really did love him, frost giant heritage or not, and (b) everyone would have welcomed him back and tried to work it out if he had given up his "the throne should be mine" obsession back during Thor. But once The Avengers came around and Loki was still trippin from not being good enough to be king of Asgard, I kind of gave up wanting him to turn out okay.
I appreciate good character development. And a huge part of Loki's character development is understanding that he was adopted, and it really has to be a big deal to realize that your kinspeople are The Enemy and no one told you until you were an adult (although Odin chose not to tell him because he didn't want Loki to grow up feeling less important, so I have a hard time feeling TOO bad for his awkward discovery). Plus his brother is good at everything, and said brother used to be an arrogant impulsive jerk. So it kind of makes sense that Loki would be jealous upset when Thor, who fell out of favor (and out of Asgard), regains his father's respect and restores his rightful place as heir to the throne. Especially if Loki doesn't understand the change that happened to Thor on earth, because while us Americans watched him change, Loki only saw before and after shots, and he wasn't really paying attention anyway.
These are all important factors to consider when understanding Loki. He's not just evil for the sake of being evil; the argument could even be made that he's not evil at all, just misdirected and malajusted, and does that necessarily make a person evil?
But people, let's have some perspective. It's not necessarily the fault of Thor or Odin that Loki turned out the way he did. Loki's got a brain; he could have figured out. He could have shut up and listened to what they were trying to tell him, because while he may feel that they have betrayed him, they never actually did. Thor loves his brother, and that's evident through both of the movies. But Thor also isn't a wuss and doesn't just give Loki what he wants so Loki will quit with the temper tantrums. Sometimes people get hurt--that's life. And when people are hurt they react in weird ways, and even that is understandable, because everyone does it. But there comes a point when you just need to GET OVER YOURSELF ALREADY. Life is about making choices. And Loki spends a good deal of his life making bad ones, and somehow this makes him a tragic hipster icon. ~~ooh look at Loki, he's all twisted and has sad puppy eyes and I just want to hug him and make it all okay.
What? Girls, for goodness sake. He isn't even badass enough to get minions--he needs to use mind control. And mind control is never okay. And did you notice the part where he monologues about power... but only to people who are obviously not as strong as him, because they're not even from the same world as he is (and by the way, it was maybe a bad idea to do it in Germany, where they're a little touchy about scary power-hungry leaders). And face it, you've got to be a little unstable to start spazzing out at the Hulk. So tell me, because I must be missing it--which part of this is attractive? He's a whiny brat who probably got that way because his dad felt bad that he was actually a frost giant, and let him get away with some stuff, which is how he turned into a greasy weasel. But once you reach a certain age, you need to start being accountable for your actions. Even IF his feelings of betrayal were justified (which really, they weren't), he still would need to eventually move on and learn to deal instead of throwing a temper tantrum.
I feel a little sympathy for people who are hurt and who go a little crazy as a result. Because we've all been there. But when you go crazy and stay crazy, and refuse to try to work it out with anyone, I don't want to hug you. Even if you do have sad puppy eyes.