I'm nearing the end of The Twilight Watch, book 3 of Lukyanenko's Watch series, and the following sentences caught my attention:
People can't get by without Others. Put two people on an uninhabited island, and you'll have a human being and an Other.
This is from Story 3, Chapter 5, before it's been confirmed that human beings can be turned into Others. It's part of Anton's internal monologue, and the way it's written makes it sound like common knowledge, not anything radical or controversial like the idea of turning a human being into an Other. And yet, it does sound like this is implying Others will be created in the absence of other Others.
Does this quote mean that a human can become an Other naturally in special circumstances? Or is there something I'm missing which is covered in more advanced lore in later books?