This weirds me out a bit- mostly because of Thor's face, lol. I'm not sure if I find this cute or just creepy. The fact that you probably accomplished both at the same time is reason enough for praise. Very nice.
How very interesting that the thing Loki gets Thor to do while under mind control is the one thing Thor would already do. Also, Thor's "Now and forever" line sorta comes off as totally creepy with that face, hehe. This really seems like it would make a great fan fic - that Loki only feels free to tell Thor he loves him under these kinds of circumstances. Tragic and powerful.
Quite a beautifully drawn picture, it really does look like a professionally done cartoon or something.