In the D&D campaign I'm running with my wife's siblings, one of them learned about how trolls regenerate within minutes of any damage not caused by fire or acid, and then asked why people don't just like. Cage them and eat them, forever. Why there aren't troll meat dungeons in the king's castle as a safeguard against sieges or famines.
And you know, I thought it was a fair question, so I said that if you eat enough troll meat, you start getting troll-y. And then I went further and just treated it like troll flesh is a general contaminant - if you eat enough troll, you'll turn into a troll, but if you bury enough dead troll flesh in a forest, the trees will start growing in strange ways, and will scream and heal and bleed when you hit them with axes.
I liked this idea. So as we played further, I just played around with the idea of Troll Origins, and I came up with something sort of like the Odyssey, but instead stealing Helios's cattle, it was Hathor's, and the horrible, awful, unending immortality was her curse of the army that pillaged her lands. A god of healing does not condemn you to die, she condemns you to live.
And then I got this fun idea for maybe the king that led the army is still kind of alive in the troll taint. Like a sort of literal fisher king. The kingdom is sick because he is, literally, the kingdom. The trees that bleed, bleed his blood and their screams are his screams. He is both the faintly green bear running down the mountain and the faintly green deer and there is no way past this without suffering. He is the entire ecosystem, and he eats nothing but himself and he dreams nothing but death and yet still, on and on and on and on, he lives.
Anyway they're traveling next session so I'm throwing this shit at them. I already have some gross ideas for like. Describing everything like it's a body (flowers red as blood, white as bone, pink as meat, grass fine as hair) then finally throwing horrible living things at them. Trees that grow eyeballs that turn and stare at them, or flowers with teeth instead of petals and trolls that speak in long dead tongues about how they wish they'd never tried to rob a god.
Anyway I'm passing this on because this is my new troll lore and I want it to become canonized in the way that all D&D lore becomes canonized: By having eople read it and go "oh, neat" then start doing that too.