Need Proof that Stanley Greaves is in Consort with Vast Ancient Powers that Gibber and Writhe Beyond the Limits of Euclidean Space?

1. His Name
Do you know anyone called 'Stanley Greaves'?  No-one has a name like that.  Except, of course, characters in H.P. Lovecraft stories.  Hmmmmm ...

2. His Diet
Stan has been observed to eat many bizarre and unpalatable things such as intestines and fish heads.  He also has a taste for cephalapods.  He has even spoken of eating dog.  The man is clearly sick.

3. His Job
He works with the mentally ill - but what sort of person sets out to associate every day with mad people?  Someone who wanted to cure them perhaps, but perhaps also someone who wanted to learn from them ...

4. His Friends
Bizarre and unsavouray types every one of them.  Rumour has it that several of his more distant associates are even more sinister and disturbing.  There are hushed whispers about a certain 'Gunny Ambrose' and even more evil talk about the feared one known only as 'Pumpkin'.

A reclusive bachelor who lives alone in a house of dusty books, reports of stange goings on in his house at night, shouts of evil names and hideous laughing in the small hours, dark hints of his own that he knows much of the hidden lore of the ancient gods - all this makes it abundantly clear that Stanley Greaves is in league with Great Cthulhu.