You know what’s going to be heartbreaking about Thor Dark World?
Loki is proven right.
At the beginning of the movie, he’s locked up for his crimes. After Asgard is attacked by the Dark Elves, Thor needs Loki to travel from one realm to the next, since he’s the only one who knows how to travel from realm to realm without the Bifrost.
This will only confirm Loki’s belief that he is “no more than another stolen relic,” locked away until someone might have use of him.