The Wikipedia entry mentioned in passing that when he ran short of money, Munthe had to rent the villa “unwillingly” to the Marchesa Luisa Casati. Why unwillingly? So I looked up the Marchesa, who was described as “a muse and patron of the arts” and a legendary figure. According to her entry in Wikipedia, the Marchesa was known for “eccentricities that delighted European society for three decades” including her penchant for parading around with two cheetahs on a leash and “wearing live snakes as jewellery.”
From there, a Google search found an excerpt from a book that mentions her dispute with Axel Munthe over the villa. He apparently decided not to rent to her after learning about her behavior, but she came anyway and stayed for several months and drove him mad with her requests. Munthe designed the villa to be as open to the air as possible, but the Marchesa — who “was dressing herself entirely in black that summer” — ordered black curtains for every window. Guests often arrived to find her reclining naked on a black rug.
She also invited a wide range of guests to the villa, including some of the gay and lesbian artists who hung out on Capri at that time, and people like the Baron Jacques d’Adelsward-Fersen, described as a “self-styled diabolist” who liked to smoke opium with the Marchesa. A separate entry from the book describes her later setting up residence in Paris with her cheetah Anaxagoras and a pet cobra named Agamemnon, and mentions that after Anaxagoras passed away she had him replaced with a stuffed black panther that had a clockwork mechanism inside that made its eyes flash and the tail swing back and forth.
Not a happy ending to this story, unfortunately — Wikipedia says the Marchesa built up debts of more than $20 million (equal to $200 million today) and had to sell her possessions. She moved to one-bedroom flat in London and later died there of a heart attack in 1957, at the age of 76. According to Wikipedia, she was buried “wearing her black and leopard skin finery and a pair of false eyelashes,” along with one of her stuffed Pekinese dogs.