Across at Butterflies and Wheels, Ophelia brings up a really interesting question. Well, it's interesting to me. 'It is very odd,' she says, 'and even somewhat mysterious, what powerful emotions we can feel about fictional characters.' And she goes on to ask what that's about and to offer a few thoughts. I don't find the question easy to answer. These are just some suggestions.
First, it's not quite a precondition of going on reading/watching etc that we care about the characters in the fiction, but it certainly helps. Speaking for myself, one reason I'll stop reading something is that I find myself not caring about any of the main protagonists - either positively or negatively. But even if this personal feeling were quite general (which it probably isn't), it wouldn't show why we do in fact often care about fictional characters. That we need to care in order to go on with the story wouldn't by itself make us care. It might just be that we never did care about fictional characters, and so there'd be no interest in stories. Yet we do, and there is.
Second, is there a similarity between the way you can care about what happens to a fictional protagonist and the way many people care about their team winning or losing? The team is real, of course, but on one level you know that victory or defeat in what is only a game doesn't matter. Yet people have invested some part of their identity in the fortunes of the team, as if they also lose when the team does - and they kind of do therefore lose, by feeling bad. So, likewise, maybe we invest something of our hopes and thereby ourselves in the fictional character, identify with him or her or, as the case may also be, identify against them when they're villainous.
I don't know how much of an explanation it is, but what the sporting analogy shows is that, as well as to real people, we attach ourselves to symbolic entities: the team stands for some community, either logically prior to or itself a consequence of the team, and we find ourselves caring about it or we bring ourselves to do so. But that kind of caring can be switched off - by turning your attention elsewhere, for example, when things go badly - in a way that concern for real people whom you are close to cannot be switched off. As Ophelia says for the case of fiction:
It is a peculiar mental state. Peculiar and delicate. It is easy to be jostled out of it - to be deeply in it one moment and the next to remember that you're sitting in a chair holding and looking at a rectangular box-shaped object packed with slices of paper with black marks on them in rows.Maybe, then, feeling for fictional characters is like identifying with a team; it's taking on an 'unreal' identity for the emotional satisfaction you derive from doing that.
Third, part of the power of fiction is that we take it as telling us something credible about real people. So though the characters are fictional rather than real, might it be that what happens to them we take as embodying things that either have really happened or could really happen to real people; and so, through the characters, we sorrow for others, rejoice or whatever, in a more abstract way?
Look, I don't know! If anyone out there has ideas about this, I'd very much like to hear them.
[Follow-up here.]