First question: What would you lose?
This has to be the first question in your mind when these things occur. What would you lose in the event you decide to make this irrevocable change?
In the case of character death, barring a name and race change, you're losing access to everything that character has unlocked. That character is a closed door from that point onward, barring some ridiculous comic book death shenanigans. (All right, I have resurrected a dead character or two, but it was always in a context that made sense for the setting.) In other cases, you're losing the ability to work with some other characters or losing certain storylines you could have otherwise explored. The details vary from instance to instance, but you're always going to lose something.
Note that this doesn't always have to be a bad thing. A marriage story arc, for instance, is very much a character boundary that can't be uncrossed. You won't be able to do certain stories any longer. At the same time, it also opens the possibility for other storylines in the future. Sometimes, you gain things in the process of losing others. But you need to start by asking what you won't be able to do any longer and determine whether you're all right with losing that.
In this case, Ms. Lady had already retired her character into alt status and hadn't played her for some time except for roleplaying. She would have to facilitate some transfers of equipment and such, but that was about it. Her main was higher-level and had more resources, to boot.
Second: How dramatic?
If your character is making a change that can't be unmade, you really don't want that change to essentially just tie up a loose end in someone else's plotline. No, you want that change to be dramatic. You want aftershocks. You want this to be something you can chat about OOC and talk about how dramatic it was when so-and-so died or when what's-her-name decided to leave the guild. You want big-scale drama.
While you know you might have a dramatic scene, you should also keep in mind what's going to come about as a result of your character's major change. Sometimes, this is even simpler than drama -- it's a merely the realization that doing X would inevitably cause Y to happen to someone else's character. It's not often the case, but sometimes your big change might force another big change in a few days time. That goes right into the cost, of course -- you need to consider the aftershocks. If it won't have any, conversely, it might not be worth doing just because no one will care.
This time around, it was going to be a very quiet scene -- a knife across the throat in a very silent place. But the impact of it was going to be haunting my main character for some time, and several others to boot. Plus, all of the rules of drama certainly implied that for the three people who were watching, this was the right time.
Third: How relevant is it?
Let's assume that you've gotten past the first two steps and both of those questions urge you to take a big plunge with your character. The next question is whether or not any of it matters for the character anyway.
There's a rule of thumb in writing that a live character is always more interesting than a dead character. Killing someone off, by necessity, means that he is no longer involved in future plots. So it's going to be relevant in all future plots involving that character, seeing as how that character will not directly be involved in any more plots.
The reason I bring this up is that sometimes you can have a big, life-changing moment in a character's story that does not actually pertain to any subsequent events. If your character gets married and then never has a single other bit of roleplaying directly pertaining to the marriage, then no matter how nice the ceremony may have been, the impact is essentially nil. You have to take into account where you actually want your character to go from this point onward, and if the big change doesn't intersect with that, maybe you should reconsider.
Obviously, we're talking about a character death, so that question is answered right out of the gate. This would mean no more stories about this character except in a posthumous sense.
Fourth: What do you want?
Ah, the big question. Is this the moment you want for your character?
In MMOs, due to the way the game is structured, you don't really have the luxury of letting character events happen without warning. A character's major events have to be big affairs, and you can't have characters just suddenly die without warning.
Your character may want any number of things. But you're the one ultimately calling the shots, so you have to ask whether or not this is what you want to do with the character from here on out because there is no turning back and you might not always be totally happy with the results. It's a moment of drama and a new complication weighed against all the possibilities you didn't capitalize on.
In this case? Ms. Lady let the knife fall. Her character died, bled out in a quiet alley, and everyone else was left to deal with the aftermath. As it turns out, that was probably the correct decision overall. But it wasn't reached frivolously.
Feedback, as always, is welcome either in the comments below or via mail to firstname.lastname@example.org. For next week's offering, I'd like to talk about development of characters compared with stagnation, where the different philosophies fit, and how to cope with the inevitable conflicts.
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.