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Given the following post, respond as if you're commenting on Reddit:
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[Harry Potter] How come Fenrir Greyback's werewolf form looks much more horrific than Professor Lupin's?

In Prisoner Of Azkaban Professor Lupin's werewolf form is hairless except for the top of his head I believe and he looks like a typical werewolf besides the hairlessness but Fenrir Greyback who always almost looks like a werewolf even in human form has I think official artwork depicting his werewolf form and it is downright horrific, he looks vile and just awful.

So how come Lupin looks mostly like a regular werewolf and Greyback looks like some demon??
gpt
Certain health and medical conditions are psychosomantic, meaning a person's state of mind can have an effect on their health. Remus mostly rejects his affliction and treats it as a curse that needs to be controlled, while Fenrir revels in being a werewolf and is so depraved that he has turned to cannibalism (which itself is known to cause insanity).