Hooks are everywhere in fiction, of course. Done correctly, a hook gives you enough of a sense of the character so that even though the entire body of work can't grind to a halt while one person's backstory is explained, you can at least get a broad picture quickly. You might know absolutely nothing about Superman, but if he's introduced saving a bunch of people from a runaway train, you know at least a little more about him than if he were sitting in the Fortress of Solitude reading a book.
More simply, hooks are a way of distilling the character's essence down to its most potent and direct form. And in roleplaying, where you will frequently be dealing with huge lists of characters, having a hook is absolutely vital. Giving other players something to latch on to from the start will mean that your character gets remembered.
This is, in fact, the point of a wide variety of the roleplaying addons available. It's the purpose of your little ID blurb in City of Heroes. It's the purpose of all sorts of things so that your character can leave an impression. You can also use these things to write entire novels, of course, but that's not really the goal. The goal is to make something short, memorable, and to the point.
Unfortunately, roleplayers tend to hate actually creating hooks.
Oh, sure, we like seeing them. But we are pretty much a gathering of narcissistic madmen who cannot wait to tell you all about our characters, whether or not you want to hear. So we tend to be resistant to creating any sort of hook, anything that other people can use to get a quick handle on our characters, because that would damage their beautiful essence. Take your hypothetical character Sven, a large angry man with a large sword, which may also be angry. It would be horrible if anyone saw Sven as just another generic berserker instead of a man with a complex past, a deep-seated need for release, anger that he's desperately afraid he can't control...
Except no, it wouldn't be horrible. "Sven is a berserker. When not in battle he seems very calm, almost distant, and speaks quietly and precisely. He is reluctant to talk about his past." That's not a great hook, but it's at least enough of one that another character can form a quick reaction to the character. It's enough detail that you get an idea of who Sven is, even if you don't know all the details. It's a starting point.
And that starting point is vital because people don't remember a 10-page biography on Sven, even if they bother to read it. They remember the silent man with heavy weapons who seemed unusually soft-spoken. And if they find there are secrets they can't tease out right away, they become more invested. It's a slow roll.
So what makes for a good hook? Brevity, obviously, is a must. Your hook should be no longer than three sentences written out, and we're not talking monstrous sentences strung together by commas like the one that you're almost finished reading here. Three brief sentences should be enough room to give a quick impression of who your character is.
And on that same note, your hook should draw someone in. Assume that you have no idea about your character beyond these three lines. Would these three lines intrigue you or would they sound boring? Would they be focusing on something immediately obvious? After you read them, are you excited to play the character? The hook should sound engaging, the sort of thing to immediately interest others in what your deal is.
Here's the strangest one, though: Your hook should be self-evident. Not every game has a place for you to put a short blurb about your character. That means that you should be putting your best foot forward to make these attributes clear about your character. In the case of Sven, when meeting people you should emphasize that this large man is speaking very quietly and calmly. But let his temper flare and then subside once or twice, just to make it clear that there's more there. Your hook is what you should be showing; telling is a last resort.
When done right, the hook is a trailer for your character, something to get other players curious about said character while still giving something to ground that curiosity in. Sure, not everything that's advertised in the trailer is going to show up perfect in the final version, but it gives a reason to get interested and a reason to get invested if you're doing it right. Plus, if you're doing it really well, it might feature an explosion or two.
I do want to come back to this topic at some point, so let me know what you think via mail to firstname.lastname@example.org or by leaving a message in the comment field. Next time around, I want to tackle an issue that was brought to my attention in a roundabout way via the comments. It involves the bathroom.
Every Friday, Eliot Lefebvre fills a column up with excellent advice on investing money, writing award-winning novels, and being elected to public office. Then he removes all of that, and you're left with Storyboard, which focuses on roleplaying in MMOs. It won't help you get elected, but it will help you pretend you did.