Honestly, cannibalism, as strange as it seems, happens in the real world, and if you joined an entirely realistic roleplay; the group leaders could set that up as a standard. Wolves for example, are commonly cannibalistic. They will not miss a chance for a meal, so that being said, every opportunity they have even if it means eating one of their own kind, they will take it. Reason for this is because they usually live in the most merciless wilderness in the world. They will eat sick or injured members of their pack, or eat any wolf that has already died. Even alphas of their own pack could become eaten by their pack members if their power over the pack dwindles.
Lions also eat one another. Same goes with bears. Same goes with hyenas. Practically many carnivorous or omnivorous animals will take the chance in eating their own kind if it means their chance of survival.
It's sad to say, Nature can leave a bittersweet taste. It's either beautiful or downright relentless.
However people who do this in roleplay; you'll never know whats in their head. They could have a sick fetish or they just want to be realistic or want a good plot to keep their roleplay going. You'll never know.