What's a good word for a person that's being followed?

According to this source here, the standard word is subject. Since Siljander wrote the book on the topic, presumably he would know.

I immediately thought of cloak-and-dagger spycraft, where the person being followed would be the mark.

There is a clear need for such a term when describing what people do on Twitter, so that there is a symmetrical term to follower. Without it sentences are stilted and table headings a nightmare (as I'm finding). If you search for 'followee' on Twitter you will find that this word is already being used to describe a person that you follow. Initially it sounds anachronistic but usage soon makes it seem natural.

Generally, the word would be leader. Twitter certainly complicates things though; I'm not sure that word really applies. Follower isn't really the same meaning in that context either, so it's hard to say what should be used. Perhaps another word should be (mis)appropriated.