An old woman begs you to find her fiancee. You ask around and discover where he is. Simple, right? Wrong. Turns out the man is dead and buried, his tombstone reading that he died from a concussion. The old lady is never seen again.
All of "I Know You" especially when you figure out who the strange man possibly is and what he meant with his final words. When John attempts to shoot him in a cutscene he is unaffected and disappears through the Great Plains, near Johns burial place
Seth Briars' backstory and what he says during the game; basically, he went from a normal guy with a family to a grave robbing lunatic. One that doesn't bathe, speaks to himself as if he has multiple personalities and is in search of a treasure that may or may not be what he's looking for. Showing what an obsession can do people and how far they might go to fulfill it.
The man talks to corpses. Even John is squicked out by this.
What about the mission Spare the Rod, Spoil the Bandit? When you finally shoot off the wood that's keeping the barn door closed, there's a cutscene of a naked body swinging on the barn rafters. Worse...there is a woman in there, so she spent who know how long terrified with the naked corpse of her friend/relative before John and the deputies could reach her. After the ordeal, you see the women, huddled together and they're traumatized, their faces are bloodied and bruised and their shirts are torn.
Look closer. The naked body is of a man. He's been castrated.
You know what makes that whole mission even worse? Those 3 women you save are the LUCKY ones! Everyone else is either dead, tortured and dead, or raped and dead. They are the only ones you were able to save, possibly after they themselves have been tortured/raped, and you almost didn't even manage that! Try not to think about how often something like this may have happened in the Real Life old west...
The unbelievable ease of literally getting away with murder is sort of indicative of the corruption of the area. Shoot an innocent man as he pleads for you not to kill him? You can pay off your bounty with less than half the money it cost you to buy the gun. You can commit some of the worst atrocities imaginable (although game mechanics keep you from doing some of the really messed-up stuff), and so long as you have the cash (possibly looted from the corpse of your victim) you're not going to suffer at all for it. Sort of shows how crappy the legal system is in RDR-world, eh?
Sad as it may seem, the game is pretty much life in the Wild, Wild West in a nutshell.
In multiplayer, there's Bear Claw Camp, where swarms of Grizzly Bears will spawn infinitely. You better hope to God you have either enough ammo to get out of the bears' vicinity or that you'll have a chance to hide in one of the three to four cabins in the area, which the bears can't enter. Though you'll be trapped there for awhile.
There's also a cougar variation of the same situation in a nearby area. Only this time, there's only one cabin in the area and the cougars are faster than you. Fortunately for you, they too can't enter the cabin, however, if you are too close to a wall, they do occasionally have their claws glitch through the wall and insta kill you.
Wolves will also spawn in infinite packs, and have the same level of surprise that cougars do.
As bad as getting Cougar'd is, just imagine that happening to you, but instead of a Fragile Speedster Cougar, you're being jumped by a Lightning BruiserBear! Spending enough time in Tall Trees can lead to this.