From the Thor script: here.
Ahhh, I can’t believe we originally had a reveal scene between Laufey and Loki and they cut it out why why would you do that it wasn’t even that long ahhh it would have been amazing.
So. What we can learn from this omitted exchange:
1. Loki wasn’t just abandoned at the temple because he was a runt. He actually was a bastard child. AND MAYBE THAT’S WHY HE’S SO SMALL. AND HAS HAIR. AND AESTHETICALLY-PLEASING FACIAL STRUCTURES. MAYBE THERE WAS INTERSPECIES MIXING. I’M LOOKING AT YOU, ODIN/LAUFEY. (Which isn’t even that far-fetched, because in the actual Norse myths, Odin had children with multiple giantesses.)
2. For Loki, Asgard is personal. Look at him lying through his teeth and wrapping all the Jotuns around his pinky finger, and even then he can’t bring himself to even pretend to offer up Asgard to them. They can think they’ll get all the rest of the Nine Realms. Asgard will always be Loki’s.
3. Part of Loki’s hatred for Laufey definitely comes from the fact that he fricking abandoned Loki to die in the snow. Look at that dig he couldn’t stop himself from making. Cue: HE JUST WANTS SOMEONE TO LOVE AND UNDERSTAND HIM FOR ONCE.