Thor is all about “mine”, possession. Afraid of Loki’s independent nature, his tendency of sorting things out by himself, Thor has to make sure his brother remembers who he belongs to: neck grabbing, handling him, chains with his name all over it, marking him, showing him around like his most precious possession, brother, my brother, saying his name, just, “mine”.
Loki is about “need me”. Thor has everything, he’s got thunder in his hands, lightning in his eyes, friends, special weapons that only he can lift, he’s got the love of everyone before they even meet him. Loki spent his life feeling replaceable, so he must feel needed: say you need me, mourn me, cry for me, say you’re nothing without me, say that losing me would shatter you. Need me.