Okay! I will try to keep this, um, within character limits for one comment. >_____>
The TD sounds like a lot of fun, if you can keep the premise from becoming too much work to moderate. Being constantly in fictional worlds has the potential to become overwhelming for you guys, but it does look like you have something built in so that we won't be. I'd like to hear more about what will be going on, then: will they be in the real world? Or will they be in some sort of limbo world outside of reality, since you mentioned that part of it is them trying to return to reality?
I'm still putting my vote in for an actual game instead of a PSL, or if it is a PSL make it open to members by invitation only so we can get some fresh blood and new characters in here. Having only the characters we have at Bellum will limit us, in a way - there are a lot of them right now, but after a few fictional worlds it will probably start getting to a point where the same characters bang their heads together over and over. New players and new characters (I say that instead of just new characters because playing/writing style can be just as important as the character concept itself) keep things from going stagnant and will provoke new challenges for existing characters by perhaps sparking some kind of response from a part of the character's personality that's never been explored before. Um, that all makes sense, right? OH and that way, following Shrew's suggestion, you'd even be able to recruit new players for roles in a story coming up, via ad communities (even something about picking up new residents inside the story world itself, which might be an interesting concept if the details can be hammered out). New players can be screened, of course, if that's a concern - perhaps through OOC conversation as well as just the application, since this is likely going to be a more closed game than Bellum, no matter what.
That said! Is each fictional world only going to be visited once? That might cause some issues, if someone applies for a character out of a certain fictional source after they've already visited that fictional source. Or will it be set on a sort of cycle, where they'll only revisit a world after enough time has passed for significant enough character development that the characters will react to the world differently? Or a second visit at a different point of the timeline... like, for Alice, a visit at the time of Alice In Wonderland and then another set during the time of Through the Looking Glass? Or Beauty and the Beast, before Beauty is taken to the Beast's castle and then again when he has allowed her to visit home?
Also, are only the fictional worlds that we have characters from going to be on the list to visit, or will they get tossed into ones that no one has a connection to, as well? Since we only have so many fictional sources that we have characters from, I'd say probably they should visit others so that the game isn't as restricted and we have more material to cover in general, but you might have already thought of that/a way around it, so that's just my $0.02.
AND (gah I will stop talking eventually I promise) are we still going for fairytales and novels written before 1910 only? Or will there be different rules so far as that goes, like "classical novels only" or a changing date on the cutoff? Not asking for any reason in particular, just something I thought should be out there!
As for changing profiles/premades, I definitely think that if it's going to be open to new people, even by invite only, there should be some updates made, even if just a basic rundown of "this is what this character did in Bellum" to show any major developments that might have happened, and those who want to can go more in depth to the point of actually rewriting sections of the profile instead of just tacking on an addendum. Echoing Shrew, if it's kept private there's no real need since we all know the characters, but the option would still be nice to have as something we could do if we wanted to. But, in that case, any major changes to the character/premade that go beyond writing down developments that have been made while in Bellum will need to be approved by mods, like... changes to abilities or transformations.