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I know I didn't come up with this but I can't remember where it's from.
The story is that I think some soldiers or knights maybe were walking through a forest and were attacked by someone/something. Their hearts were ripped out but they didn't die so now they walk around the forest, carrying and pumping their hearts, not living or dead.
I feel like it was a story told to the main character, probably in a book but maybe not, as a sort of incidental/local colour tale that was not relevant to the plot.
Please help, where have I got this from?