Antagonist's presence in the story
Question: I am working on a series of 3 or four books telling one central story. How do you write a villain like Sauron from Lord of the Rings who has really no physical presence in the first book or two?
Well, the answer for Tolkein was to introduce agents of the villain -- Nazgul, Saruman, orcs, etc. and make the villain somewhat of a mystery. I don't recall, in fact, if Sauron ever makes an appearance in the story except at great distance. (We see the Eye, but that's just his crystal ball.)
The downside of that approach is that we get very little sense of Sauron's personality. The character becomes very one-dimensional. These days, it has become more fashionable to create villains with more depth who the reader can feel some sympathy or even empathy for.
In fact, many of Sauron's agents seem pretty flat as characters -- the Nazgul in particular.
I think the most important thing you could do to make your disembodied villain more tangible is to give him/her/it the ability to communicate with other characters. Conversation reveals the character's mind which makes him more real. Think of how we get to know Tom Riddle through the diary messages in Harry Potter and the Chamber of Secrets
. You could do the same
thing with text messages. Of course, the scary thing about Tom and other people you meet in cyber space is that, if you can't see where they keep their brain, how can you really trust them?
(Perhaps you're familiar with the Turing test, which says that artificial intelligence is real if you can text-chat with the machine and can't tell it's not human.)
The other thing you might do is create agents for the villain who are three-dimensional characters with physical form. We can feel sympathy for a character like Saruman or Denethor or even Theoden who has been seduced by evil much more than a purely evil character.
Another technique is to create physical symbols or avatars for the disembodied villain. These could be objects (like Tom Riddle's diary) or animals (birds or snakes have been used), or even houses. In other words, even though these things cannot communicate, their presence becomes a symbol of the evil force at work in the world.
Sometimes, however, this approach can lead to the villain become less like a character and more like a force of nature, as in Hitchcock's film, The Birds
or other disaster stories. In other words, the threat is not so much an antagonist as a backdrop for the real story which concerns the other characters.
Hope that helps.