It’s a well known story in fandom that the first science fiction writing couple met when Henry Kuttner wrote to C.L. Moore, expressing admiration for Moore’s fiction, and discovering only upon her response that she was a she. What’s less known is that H.P. Lovecraft occasioned the initial letter.
One small detail in Lovecraft’s letters to Kuttner proved to be of great moment in the subsequent history of weird, fantasy, and science fiction. In May, he casually asked Kuttner to pass on some photographs of Salem and Marblehead to C.L. Moore once Kuttner himself had finished with thim; and it was in this way that Moore and Kuttner became acquainted.
And in 1942, when Bob and Leslyn Heinlein moved for Bob’s Philadelphia Naval Shipyard job, Kuttner and Moore stayed in the Heinleins’ house in Laurel Canyon. From Robert A. Heinlein: In Dialogue with His Century, vol. I:
She [Leslyn] even practiced witchcraft – “white witchcraft,” in the old pagan tradation of northern Europe, though she didn’t (so far as Robert knew) belong to an actual coven. […]
First she had placed wards around the house to protect against the ghosts the Kuttners had noticed in 1942 – “especially one against a thing that keeps trying to come up the basement steps.”