Quote from: Cave Bear;1109188Except for all the examples of physical corruption that do indeed show up in HPL's works as pointed out in examples within this very thread.

With the exception of the Dreamlands, physical changes tend (ghouls possibly excepted) to be the result of inherited traits not learning or using the Mythos as in, "Wow! Bob's character just grew a third eye in his stomach after reading De Vermis Mysteris!" or "Ewwww! Sue's character just grew another tentacle after using that whistle to summon a Byakhee. Wasn't the one she grew after drinking that Space Mead enough for her?" That sort of corruption is something seen in settings other than Lovecraft.

Quote from: Bren;1109236With the exception of the Dreamlands, physical changes tend (ghouls possibly excepted) to be the result of inherited traits not learning or using the Mythos as in, "Wow! Bob's character just grew a third eye in his stomach after reading De Vermis Mysteris!" or "Ewwww! Sue's character just grew another tentacle after using that whistle to summon a Byakhee. Wasn't the one she grew after drinking that Space Mead enough for her?" That sort of corruption is something seen in settings other than Lovecraft.

Yes, I think that's right. Apart from the Ghouls, 'corruption' is due to Tainted Blood - Nature over Nurture. Growing tentacles is a Warhammer thing not an HPL thing and is associated with something like D&D's Far Realm creeping in from Outside. But in HPL there is no Outside; the Outer Gods are a natural part of the Cosmos.

Quote from: S'mon;1109277Yes, I think that's right. Apart from the Ghouls, 'corruption' is due to Tainted Blood - Nature over Nurture. Growing tentacles is a Warhammer thing not an HPL thing and is associated with something like D&D's Far Realm creeping in from Outside. But in HPL there is no Outside; the Outer Gods are a natural part of the Cosmos.

Without bothering to look up specifics I'm pretty sure there are references in some stories of entities coming from 'outside'. Whatever that means in the context of the Mythos I'm not sure, but they are presented as distinctly NOT natural to our corner of space... as having a corrupting influence on people and places. It's not so overt as the spontaneous growth of tentacles, but Colour alone is enough, IMO, to allow for having physical mutations due to prolongued exposure. If you want them.
There are other mutants as well, The Beast In The Cave had been a man. The Martenses in The Lurking Fear had been human. There's no mention that I recall of them mating with outre things.

I wouldn't a lot of sudden/random big mutations (ala Warhammer), or mutations for minor dealings (read a book, roll for crab claws)... but subtle effects, maybe just a reduction (or increase?) in Appearance might capture a vague sense that the character's exposure has left them tainted.