This is one of the creepiest secret mysteries in Red Dead Redemption 2 and part of it may still be unsolved. Between 4am - 5am you can find a red glowing satanic pentagram in a tiny hut north-west of Van Horn Trading Post, in the woods. If you make a camp there at night, a woman can show up and tell you of a demon that consumes the villagers. She starts to get frightened of you and tries to run off. The pentagram is actually under the shack, it's unclear if there's more to be done here, potentially a ritual or sacrifice. Anyway, check it out, it's a rather creepy encounter.