Let's talk about this scene. It's one of the most popular, and the writers and actors knew exactly what they were doing when they filmed it. This is going to be a LONG, long post because I will be breaking down and analyzing looks as well as dialog. Don't worry, I will add in a cut! Let's start with the look on Bilbo's face. Specifically, I've slowed the GIF down so you can get a good look at his face.
Bilbo stated quite clearly to Gandalf the night before this that he was not afraid of Thorin, but he is not so naive as to think that he will stay in Thorin's good graces after this. Hitched breath, sluggish movement, rapid blinking, and a look of dread on his face. This is a funeral march for whatever future might have been brewing over the course of the journey.
Thorin, by comparison, is almost slow to comprehend. There is doubt about what he is hearing written all over his features. He shakes his head and says "you" like he expected to turn around and see someone else standing there using Bilbo's voice. What I really want to get at is the conversation right after. Because it's always struck me that Thorin and Bilbo are not having the same conversation with each other.
"I took it as my fourteenth share," followed immediately by "You would steal from me?"
Now, it's, of course, important to note that Thorin is at peak dragon sickness at the moment and not in his right mind. That said, Bilbo stealing something from him was truly the last thing he could have possibly imagined happening. He suspected his kin less than a day ago but never Bilbo. I've said this in a previous deep dive, but the way that the dragon sickness reconciled Thorin's love for Bilbo and the gold was to place them in the same category. You don't expect what is entirely yours to be capable of theft. We're going to skip ahead slightly in the next GIF.
Ok, so this is where we start to see the conversation diverge. Bilbo says, "Steal from you? No, no. I'm a burglar, but I like to think I'm an honest one." Clearly trying to articulate to Thorin and the entire company that he didn't do this as a betrayal or out of greed. Thorin's response is chilling and very telling.
In the first GIF, I have no subtitles because I want you to look at his face, not what he's saying. This is the laughter and smile of a madman who just had the last thread tethering him from true madness cut. He descends very quickly from here.
Now, "You have no claim over me" is a very strong statement. In his mind, the gold is his and bound to him in every way. Bilbo, after this, is desperate. His words are desperate, and his expression is desperate. But what's more heartbreaking is the look in Thorn's eyes. Like the real Thorin is trapped behind those pretty blues, helpless to do anything.
Then, finally, after all of this, we have the full snap. The final break.
"Throw him from the ramparts."
This single line gives us probably the most heartbreaking look in the entire movie. To me, even more so than Thorin's death. This is the true "end" the final break. Bilbo's head was bent low. He was willing to take the vitriol the hate. He understood where it was coming from and was prepared for it. But those 5 words ended everything. Thorin is gone, and Bilbo knows that now.
We haven't seen true fear in Bilbo. Not once. The closest we got was when he was about to charge an orc but even that was not fear alone. There was determination and resolve that colored his expression.
That last hollow look in Bilbo's eyes is properly terrified yet if I had to name this GIF I wouldn't name it terror I would name it
Loss.