H.P. Lovecraft was one weird dude. After having read a lot about him (and after having bought a collection of his works), it seems that "weird" doesn't seem to be quite enough. And that's me saying this. He seems to have been a victim of a sort of social anxiety disorder, except from among his letters it seems that he also had a "nervous disposition" while alone, or while living with his mother and aunts. His mother's mental and emotional spiral wouldn't have helped, and she ended up in Butler, the same asylum his father died in--though his father undoubtedly had syphilis, while he and his mother were simply...nervous. (Mary Karr's mother was apparently the same, and the word "nervous" was used to mean someone who was barely functionally insane.)
Lovecraft married and moved to NYC, but the marriage didn't last long, and his wife complained that he was more comfortable communicating with her through letters. He moved back to RI; she moved to Cleveland and later to CA after she re-married. He then proceeded to write maybe more letters than anyone else, ever. One scholar places the number of letters at over 200,000; one wonders how much more fiction he could have written. Yet, he was more comfortable writing letters, and getting comfortable seemed to be his life's work. His letters, perhaps more than his writing, may prove to be his most lasting legacy.
His fame doesn't rest upon that much fiction, and much of that fiction is just plain bad. Yet the good is very good, of its type. Storyline and plot were not important. More than Poe, Lovecraft was interested in atmosphere and feeling, and he got those across very well, as well as, or better than, even Poe. Reading Lovecraft is to feel dread, even if you don't know what you're feeling dread about, exactly. Reading his best is like having a nightmare you don't understand, but that which makes you fear and dread.
His fiction and letters had a major similarity: fear of others, or, more exactly, Others. His most ardent fans are forced to admit his rampant racism; his racism is flat-out fear. Scholars point to his NYC days, in which he was jobless. He felt immigrants took job opportunities from him. Probably it was his demeanor and nervousness. Would you hire this guy? Upon returning to RI, he quickly decided that he would work from home, writing, ghostwriting, editing and corresponding. He did not ever become otherwise employed. Due to his mother and aunts' spoiling of him, he perhaps never had to. (To be a fly on that wall...)
When he knew that death was close by (colon cancer), he appointed a teenage fan from Florida to be his literary executor, which one scholar said was like hiring you or I to lead an army platoon into battle. This kid promptly gave over most of the works to August Derleth, Lovecraft's aunts, and a university, thereby causing one of the most confusing copyright wrangles in the history of literature. Who owns the rights? The writing from the 20s, nobody, as they are now in the public domain. Perhaps everything now is. Or the aunts, or Derleth, got cheated. It is further now established that the Cthulu Mythos is more Derleth than Lovecraft, which makes sense to me, as Lovecraft often stated that he was after atmosphere and feeling, plot be damned, and the Mythos stories clearly show a consistent and connected sort of plotline, in a Good vs. Evil sort of way. Lovecraft, an avowed atheist and overall nihilist (and elitist), probably did not believe in a good vs. evil distinction.
His stories, like his life, defy simple explanation, besides to say that they are an exercise in supreme oddity.