Everybody probably already saw it

please, Marvel put Norse Mythology in with a bunch of super heroes. Questions invalid

 

Which is also what confused the hell out of me at first. Still not sure how it works, but...somehow it does...just barely.

 

Loki was a villain but he was also a sort of a slave, imo. After being banished he begged Thanos for help, so in a way, Thanos is the main villain.
Loki just wanted revenge on his brother and Earth. I think Tom Hiddleston did an amazing job at acting like a big scary villain, but at the same time, in a subtle way, showing that he's just a scared kid that's being used by something way more powerful. But hey, that's my opinion.

Also, for the people who complain that certain characters don't act like their respective comic-book characters, the Marvel Movie Universe is different from the comic-books and could be viewed as an entirely new Universe on its own. Again, my opinion. (I have no experience with comic universes)