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Tear Jerker: The Hobbit
The deaths of Thorin, Fíli, and Kíli, and particularly the Final Speech of the former:
"There is more in you of good than you know, child of the kindly West. Some courage, and some wisdom, blended in measure. If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. But sad or merry, I must leave it now. Farewell."
Fíli and Kíli dying is understated in itself, but throughout the book the narration makes it clear that they are the youngest and merriest of the group, which, when you know about how Tolkien fought in WWI, makes the terrible waste of young men's lives all the more poignant.
Seeing Frodo in the beginning, helping Bilbo get ready for his birthday party. He looks so happy and innocent and you cannot help but smile/squee at his young self. Then you remember that this is his last truly happy day. From here on out, it's all downhill for him. He'll never be truly happy again once he's become the Ringbearer.
The lyrics to the song "Misty Mountains" are absolutely heartbreaking, as it is a song about the destruction of Erebor.
The death of Sebastian, Radagast's hedgehog. He gets better, sure, but still.
The look on Radagast's face is heartbreaking all by itself.
Yeah considering he doted on him and named him and his panic at trying to cure him, he probably thought of Sebastian and all the animals in the forest as his children. Any parent who's ever had a sick child knows the same fear and dread he was going through.
The forest creatures dying as the Shadow spreads over Greenwood/Mirkwood.
Thorin's story. His city razed, his people mostly dead (including his grandfather, little brother, and most likely his father), on a seemingly hopeless quest... When he turns around after Balin's Info Dump and just looks so broken, you just want to give the poor guy a hug.
The look on Gollum's face when he knows his "precious" is lost. Bilbo can't even try to kill him after that. And even though you know what will happen with him later on, you can't help but feel at least a tad sorry for him.
Indeed, Gollum's face was of a lost boy, looking for his mother. Slow tears and all, and a complete sadness. This is how Gollum is in reality: not a vengeful monster, or a dark lord, he's just a little guy who succumbed to the Ring's evil.
Its his eyes for me, especially when The Sméagol side looks at Bilbo and they remind you of a child who doesn't understand what's going on or what just happened. How sad and broken he looks as Sméagol was basically just a child being bullied around by The Gollum part into doing bad things
For those who know how the book ends, many of the dwarves being as likable as they are. Especially Fíli and Kíli.
Almost as a precursor to this, during the stone giants scene the dwarves are separated when part of the cliff they are on comes alive, with Fíli and a few others being carried away. Seeing Kíli reaching out helplessly to try and grab his brother's hand is bad enough, but when the giant falls and appears to have crushed the group Thorin just about loses his composure and runs towards the wreckage screaming Fíli's name. Never mind that the rest might also have died - in the end, Thorin values his nephews above all.
Adding to this (combined with Fridge Horror): Ori, that adorable little dwarf who, at the party, politely asks Bilbo where he can put his plate, and murmurs about the green food in Rivendell, will - fifty/sixty or so years later - be writing the horrific words Gandalf reads in the Mines of Moria during Fellowship of the Ring: "We cannot get out. They are coming."
Doubly so, for those who've played The Lord of the Rings Online, as, during one point, you play Ori during the final stand in the Chamber of Mazarbul (where Balin's tomb is). And the instance there only ends when Ori dies. Which how Adorkable and likeable he is that much more painful here.
And he will die on an expedition led by the equally ill-fated Balin, the kind, wise, Cool Old Guy of the dwarves, Bilbo's dear friend and one of the most developed characters.
There was a third member of their party who joined their expedition: Óin (the dwarf who used an ear-horn), who was unceremoniously eaten by the Watcher in the Water (the giant squid-thing that almost got Frodo in the first movie). He also happens to be Gimli's uncle and Glóin's brother.
The plight of the Erebor dwarves is one horrid tearjerker after another. Not only do they lose Erebor and all the priceless relics within, but Moria and dozens of other strongholds began to fall one after another. This would be hard for any people to endure, but dwarves in particular value their ancestral homes in a way few humans can comprehend.
If this wasn’t bad enough, according to the book, after the Battle of Azanulbizar where Thorin fought Azog there were so many dwarven casualties that they couldn’t bury them in time before they were claimed “By wolves or worse”. They were forced to cremate the dead instead, which the dwarves consider sacrilege. A short while ago, Smaug incinerated hundreds of dwarves, effectively killing them and desecrating their bodies simultaneously. A few years later, a similar desecration occurred, only this time the dwarves were forced to inflict it on themselves. On the other hand, this becomes a point of pride for the dwarves' families - "He was a burned dwarf" is a statement of pride, not shame.
And, in addition to losing Erebor, the beginning of Thorin's grudge against the elves. Thranduil shows up with his army, but when he sees there's nothing they can do against Smaug, he retreats. (Several viewers have criticized him for this, but really, what was he supposed to do against a dragon?) It's not as if he doesn't care, though; you can see by the look on his face that he hates having to do this. Unfortunately you can also see the look on Thorin's face, thus witnessing his despair and utter betrayal. Their next meeting is not going to be pretty.
It makes sense considering Thranduil's past. The last time his people helped another army out led to the deaths of 2/3 of their army including Thranduil's father Oropher, and that was for the fate of all Middle-Earth. Thranduil wasn't going to risk that again for one dwarf kingdom. In addition, Mirkwood was fighting it's own battles against the darkness that was slowly taking over and he couldn't spare any of his warriors for a battle he knew would lose.
“Oropher was slain in the first assault on Morder, rushing forward at the head of his most doughty warriors before Gil-galad had given the signal for the advance. Thranduil his son survived, but when the war ended and Sauron was slain (as it seemed) he lead back home barely a third of the army that had marched to war.” -The Unfinished Tales
The look on Bofur's face after Bilbo says that he and the other dwarves "don't belong anywhere". You can tell he's trying to hide how much those words hurt him, and he still wishes Bilbo the best of luck with a smile.
Bilbo realizing how insensitive his comment was and almost immediately attempting to backtrack on it more than likely helped assuage the blow.
On top of that, Bilbo's face as he realizes that the dwarves are fighting for exactly what he can scurry off to any time, and that is why he has to stay. His conversation with Bofur ties in nicely with his speech to Thorin near the end.
One of the goblin's smashing Óin's ear-horn. It's just so cruel that it's hard not to feel sorry for the poor old dwarf.
In the extended Edition, we see Thorin overhearing Elrond and Gandalf talking about how insanity runs in Thorin's family. Despite his bluster, it's clear that Thorin feels the weight of what he is attempting and having his sanity questioned and his father and grandfather spoken of is like a knife in his heart.
The computer game
The Hobbit computer game is mostly a brightly-colored, action-adventure version of Tolkien'sbook. Then you get to Mirkwood, and meet Corwin, a soldier from Laketown, whose entire party was just killed by spiders, including his brother. The music alone will tear your heart out.