Wargs (the wolf like mythical creatures in the movie) are not dogs, not by a mile. Let alone, they are by definition evil. The only emotion their deaths may trigger is cheering.
[SPOILER AHEAD]
A major character falls from a mountain cliff and is believed to have died from the fall. However, it later turns out that he is alive, and almost unharmed.
Another major character that was believed to have died in the first movie is revealed to be alive and comes back to support his friends.
Two main characters are believed to have died for a very short amount of time as well. They are okay.
The only instance of more important character (not really a major character) dying is an elve during the battle of Helms Deep. He appeared in the first movie and is a friend of Aragorn and Legolas. The scene is quite dramatic but not too emotional.
You could argue that Gollum is a presentation of someone with DID. It is explained by Gandalf in the first movie that one part of Gollum hates himself and another part of him likes himself. Throughout the movie there are several scenes where Gollum/his two parts are talking with each other and they have different aims.
[Spoiler ahead]
At some point, Gollum/Smeagul is able to drive his „bad part” Gollum out. From that point the „positive side” Smeagul is the only personality. Later in the movie Smeagul is hurt deeply by some guards and believes that Frodo is responsible for some of this harm. Due to this pain Gollum comes back and we see the two personalities fight against each other again.
There are implications that Wormtongue obsessively stalks Eowyn (her brother Eomer angrily confronts him about this). In one scene Wormtongue is shown lurking in the shadows while watching as Eowyn grieves for her deceased cousin, before he proceeds to touch her face while speaking of her cold beauty and she trembles and stares at him in fear and disgust.
Sméagol/Gollum is shown to regularly manipulate Frodo and Sam, exploiting Sam’s distrust and Frodo’s mercy and growing attachment to the Ring to slowly pit them against each other.
There is no addiction in form of addiction to drugs/alcohol/etc., but the ring's power has similar effects if exposed to it for too long.
You could say that Gollum/Smeagul is a very accurate presentation of addiction.
about 1 hour and 37 minutes in, gollum runs over with 2 dead (and very fake looking) rabbits. he snaps one of their bones which is quite disturbing but it doesn’t show their deaths. also, gollum is trying to catch a fish about 1 hour and 25 minutes in
When Frodo, Sam, and Gollum are going through the Dead Marshes, Frodo looks into the water and appears to be either hypnotized or otherwise influenced by the spirit he sees floating. He collapses into the water and the ghostly spirits reach for him.
A subplot involves a scheming male character who is plotting to "have" a female character as a "reward" for his evil deeds. He systematically isolates her from her family. There is a scene where he finds her alone and vulnerable, and says some creepy stuff to her (not explicitly sexual, but it does have to do with being alone, trapped and defenseless at night). He touches her shoulder, then her cheek, both unwanted. She is plainly afraid of him. Although it doesn't go far physically, emotionally it is quite terrifying.
Golem breaks a rabbit in half. It’s already dead, but it shows it and makes a nasty sound. Ghimli also breaks an orc’s neck in the battle with the Worgen.
There is some blood but, especially considering the scope of the battles, I would not call it excessive. Most deaths are bloodless or there is some black orc blood. Exposed organs and gritty things like that are never shown.
Many Uruk-hai die in the battle at Helms Deep. Several elves, including one from the first movie, are also killed there. It seems at first that two hobbits may be dead but they turn up alive.
There is a location called the Dead Marshes, where ghostly figures are shown in the water and try to drown Frodo. A Ringwraith is also briefly seen riding a wyvern in the same area.
A withered Theoden is possessed by Saruman at the beginning of the movie, but is quickly exorcised by Gandalf and returned to his more lively state. The evil effects of Sauron’s influence via the Ring also become more apparent in this movie, with Frodo beginning to become more irritable, irrational and aggressive towards Sam.
Extended edition only: One thing that put me on edge is when pippin and merry are with the orks and they make merry drink something but he doesn’t v* simply coughs it up
As someone who has a few friends with DID/OSDD i can say that after asking them Gollum isn't a misinterpretation - good alter vs bad alter thing is present but two of my friends that are systems said two things - one said they do in fact have such a situation where there are two alters that are polar opposites and the second one said they know a system with such a struggle. So if you acknowledge and accept that this is a thing that is happening inside some systems - totally no problemo :)
Gollum DEFINITELY suffers from ptsd that was caused by Mordor and the ring itself. Specifically it's the Smeagol part of him that seems to be scared and all
There are numerous instances of male characters openly expressing emotions as well as platonic and familial affection for each other in various ways (crying, hugging, hand holding, kissing on the forehead, etc.). This is treated as normal and expected, and nobody is subjected to shame or ridicule for these displays at any point.
Not directly. The ending is open since there is a third movie. Many people died and the mood is not the best but the last big battle was won, so there is still hope.