an indie kid isn't any of those things. They're really just nerds who aren't nerdy. What I mean by this is that they don't have an unhealthy LOVE of school (they are smart, so their grades will be decent, but they don't go to freaky color coded flashcard frenzies). They dress however they want, whereas regular nerds just fail at dressing like everyone else. They listen to indie music (obviously) but they don't always brag about it. If they wear jeans, a tshirt, and converse it's because they FEEL like it, not cause they're trying to be indie. They hang with other indie kids, nerds, and normal people.
The kid you see listening to their ipod while standing next to their frantically studying friends, then witness an hour later actively involved in some nerdy debate, that's an indie kid.