Yes, the films are strictly fictional and only loosely inspired by the lore, but the first Thor movie did a lovely job of presenting the complexities of Loki as an outsider in Asgard. He’s perpetually torn between his origins and the society which took him in, and consumed by the burning desire to just be accepted as equal, or recognized for what he can offer. Frustration mounts because he’s always being overlooked and cast to the side as inherently less worthy than, say, Thor. Even though he was brought into the fold by Óðinn himself he’s still regarded as the weird tag-a-long riding on Thor’s coat tails (er, cape?), which mirrors the lore pretty closely. He’s not inherently a bad guy, but circumstances push him past his breaking point and he starts making some pretty villainous choices, both on screen and in tales of old.