"Inviting Pedobear to the party was not fun nor appreciated."
Here, used to be here. The premise is that the characters are on the internet — originally they were on a LiveJournal community and now they're on a Dreamwidth community, because you can never be too meta. As such, one of the rare cases where Trapped in Another World is averted (unless you manage to get worldhopped somewhere and have your transport ditch you.)
This game provides examples of:
Alternate Universe: Some of the casts have been in the game so long and so strongly affected by its events that they derail canon. The most obvious of these is Avatar: The Last Airbender — for a while, Azula was the Fire Lord, with Ozai in hiding and presumed dead. The Gundam 00 cast has diverged significantly as well, with a number of canon deaths averted, and the Phoenix Wright-era Ace Attorney cast seems to be actively avoiding the future that the Apollo Justice-era cast lives in. The Resident Evil cast did its very, very best to screw with the timeline by bringing back just about every villain that should have been dead and putting them all after Resident Evil 5. Also, blowing up the White House.
Artistic Age: J flirts with Setsuna yet treats Makoto as his child, despite Makoto being around the same age as Setsuna and likely a few years older. This is in part referencing Precure fandom's tendency to claim that Fresh Pretty Cure! makes the characters look older than they are (read: older than the pre-Fresh art style made their age-cohorts look) and Key Visual Arts hatedom's complaint that the mid-to-late teen characters look like children to them.
Berserk Button: Many characters have them. For example: you can do whatever you want to most people, but if you threaten Lilith or Cuddy, Azula will fuck your shit up— or at least try really, really hard to.
Big Screwed-Up Family: Quite a few of these, some even holding over from the Family Virus which has popped up a couple times. There's been Cuddy and her adopted kids, the TARDIS family, and maybe even the Creeper Island crew too. Though that last one leads to some rather unfortunate implications.
Breaking the Fourth Wall: One April Fools' prank culminated in Kaito managing to post on the OOC community searching for the people behind the viruses, and letting several other characters out into the post with him.
2012's April Fools' prank: characters writing applications for other characters. (And one player apping himself.) It even spilled over to rpanons.
2013's April Fools' prank was actually a number of pranks. One character posted on the OOC community again, another mun announced plans to move all the players into a mansion, and in a call back to the previous year, the person who apped himself in 2012 promptly dropped himself.
Break the Cutie: Retasu, Retasu, Retasu. Apparently being shot down before you even confess your feelings because the guy you like is in his early twenties and you're in high school isn't enough, and they have to add facing your worst fear and being locked up, being manipulated to destroy a number of worlds (and very nearly going through with it) because you think it will protect said object of affection's happiness, being told to your face by someone you trusted that you're worthless, having Forgotten Birthday subverted when the surprise party is postponed and never actually ends up happening so you really do think everyone forgot you (because the host was too busy turning evil because of a virus and blackmailing and verbally tearing apart everyone he cares about), being one of those people and being told you have no free will, then losing him after you never had the guts to say anything about it, and then watching everyone you care about die.
Canon Discontinuity: Players who feel that their early days of playing a character left something to be desired will often employ this, either officially or unofficially.
The Engrish virus was officially disowned after some drama with people outside of the game mocking ESL muns inside it made the subject matter hit a bit close to home. It has never been listed on a grab bag list since and has rarely ever been referenced, making it officially Old Shame.
Cannot Keep a Secret: There was a virus that made everyone confess their biggest secrets. Side effects included scores of love confessions, relationship drama, and nearly every magical girl on the community revealing her secret identity to the public.
Cerebus Syndrome: A gentle example, but while the game is still based around humour and laid-back fun, it's a hell of a lot more serious and dark at times than it ever was during the first year or so of its life. Small outbursts of wank or drama made the almost non-existant modding of those times impossible, as did the growth of the game. If one looks at the posts from that time, it's hard to believe it's the same game. DDD really grew the beard.
Clark Kenting: Failed horribly by Tsubomi as her identity as Cure Blossom was accidentally leaked three days before she officially appeared in game. Having the rest of the Pretty Cures nonchalantly introduce themselves and call her by her Cure name was mixed in with her flailing and wondering how she messed up.
Continuity Nod: When a new character appears who has been played before, characters who were around back then WILL remember it.
It usually leads to the new version of the character saying something like Have We Met?? unless...
Laser-Guided Amnesia: Unless, of course, the new mun forces CR amnesia, as the new Deadman Wonderland cast has done. A lot of characters who were only around for one or two posts before dropping similarly undergo a Ret Gone for the sake of ease.
During the Zombieland event, the mall they were trapped in was full of not just American chain stores, but chain stores that would normally be found only in America — Macy's, Dillard's, Barnes & Noble, etc.
Distressed Dude: Issei often, including the Opposite Doppelganger virus, the Bad End virus, and the xDere virus (though the kidnapping plot from the last one was retconned entirely out of existence). Usually causing complexes in his boyfriend and admirers about the inability to rescue Issei from anything.
Enemy Without: The community was drawn into the plot of Persona 4, and once it finished, there was a Shadow event affecting all of the other characters' worlds. The event was popular enough that it spawned a just-for-fun spinoff community, and a second Shadow event occurred later, though it didn't prove as successful.
Issei and Diarmuid, who did eventually hook up, had the entire community seeing it before they admitted it to each other. Including Kefka, who's repulsed by romance in general. And Retasu, who's in love with Issei.
Now that Satan Is Good has gotten involved, it's basically a huge creeper-off.
The Faceless: Orlando during his time, since he was an unbodied entity who was eventually given a robot form. The Major was this also temporarily after she was seemingly killed through canon events. Currently Regene fulfills this role, with all of his comments and posts hiding his icons to keep the rest of the cast from knowing about him.
On the flip side, sometimes either a virus or simply the influence of the community members will send characters on a Heel-Face Turn. Two that fall into this category, for example, are Nena and Michael Trinity. They've been with the community so long, they actually listen (sort of) to Tieria and have come to join the main Celestial Being crew as backup Meisters.
Fountain of Youth: One of the most well-loved viruses and one that's popped up a few times is the good old Age Regression virus...
Genre Launch: Although the setting is a website rather than a physical place that characters meet in, because nobody is taken from their worlds permanently when they're brought together, DDD can be considered the first reverse jamjar.
Go Karting with Bowser: Unless a villain is actively doing something terrible right this minute, they're usually just ignored by their enemies and treated at least tentatively civilly by everybody else.
Hero of Another Story: The game provides many literal examples—between the setup of characters remaining in their canon worlds and the frequent absence of major characters from a given cast, it's not uncommon to see minor recurring NPCs who are actually the stars of whatever series they're from.
High School AU: There was a high school AU virus as well as a few similar ones (college AU and Hogwarts AU).
In Spite of a Nail: During the College AU virus, Issei is again about to confess his feelings (albeit to Louis, because virus), but this time he's meaning to do it rather than trying to avoid it because he never closed himself off. Similarly, even though none of the obstacles to Retasu working up the nerve to tell Issei how she feels existed in this world, and she finally ends up confessing, he still has to turn her down. Even so, this version of events doesn't end up endangering the multiverse.
Island Base: Creeper Island, obviously. But not anymore, after Wesker blew it up more out of petulance than anything else. Also because Regene had revamped the security system and in essence had control over the island, which Wesker wasn't happy about. But mostly because the muns were bored.
It Won't Turn Off: Usually used with introduction posts or for those who haven't posted in a while, as until you accept it, the community likes to keep your browser open to its page and won't let you go anywhere else.
Jerkass Gods: During the time DDD allowed them, pretty much every God that came through the game was some form of this. Eros deserves a special mention for his...memorable events. The current example would be Eris.
Keeping Secrets Sucks: Not only can characters become aware of their own canon, due to the nature of the game, cast members can come from different points in their respective canon timeline. While some canons or characters can Screw Destiny, others choose to or have to keep knowledge of the future from affecting their castmates in the past. Among others, since the time Evangelion characters were introduced to the community, one or several of the characters were required to keep information about their position in the timeline secret from the one lagging behind. In particular, Kaworu has continuously rallied others from his canon and close acquaintances to keep quiet due to potentially grievous consequences on their home world. Not that they weren't already bad enough.
Kink Meme: It has one every so often, and it's really popular. Occasionally, there's even an IC kink meme.
Some of the characters have looked themselves or others up on Wikipedia, some have trolled Pixiv for embarrassing pictures, and some of them are even aware that others and themselves are from fictional series. The Tenth Doctor has even admitted to watching his own series.
Loophole Abuse: In the HeartCatch Pretty Cure! canon, the girls had to fight a previous Pretty Cure to obtain a special item, the Heartcatch Mirage. In canon, Tsubomi's grandmother gives this job to her fairy partner, Coupe. Thanks to the wonders of the Duck, Tsubomi, Itsuki and Erika have to fight Nagisa, Honoka and Karen.
Magical Girl Warrior: The game has had two or three Precures and two or three Sailor Senshi around at a time for years, but in 2013, there was an explosion of them with tons of series represented. Those responsible protest, "I only meant to enable one person... maybe two...".
Mama Bear: During her 3+ years in the game, Lisa Cuddy adopted four children, only one of whom was canon and not a character in the game. She was this to all of them, particularly when they were threatened by outside forces. For a while there was even a running joke that she was going to punch Fire Lord Ozai in the face.
Marry Them All: Considered by Issei when he finally faces the fact that he's still got a harem and it isn't going away. Though they all think they might like it to some degree or another, they all see through it.
"(...)when you make decisions about your love life, think about how you feel, too. We all love you, but are you just trying to make us happy?"
Must Make Amends: Kano learns that Kanna lived a thousand years before her in the same world and finds out what happened, but hesitates to tell her for fear of the side effects of an attempt to Set Right What Once Went Wrong... both serious and selfish, and also because she isn't completely sure it's her. It is. Her Shadow shoved this in her face, and since Kanna came back to the community, now in the afterlife after the curse was broken offscreen, Kano has been doing everything she can for her just to make up for it. Kanna, for her part, wants Kano to stop blaming herself.
And the 4Chan account too, where players were able to troll the comm with Pedobear and others.
Not Himself: One popular virus involved the switching of alignments causing a ruckus on the community. It's one of the virus that's been repeated a good few times. The most memorable example from the very first instance was Demyx, whose subtle but incredibly creepy change left mental scarring on some oldbies.
Not Me This Time: The second that Ange mysteriously disappears, EVA-Beatrice makes a point of publicly claiming that it isn't her fault.
Off the Rails: The common term for this would be "Canon Derail", in which a world's canon events are knocked off so far that a brand new timeline is made, especially if it's done by one insignificant action. Most, but not all, worlds have been affected by it.
Online Alias: Everyone *has* one since it's Dreamwidth, but they're infrequently commented on.
Precision F-Strike: Kefka reveals that Retasu's in love with Issei, has been for long enough to see him seek comfort from a number of other people before finally finding someone he did love (hint: it's not her), and the only reason she's working for Scratch, putting billions of lives in danger without realizing it, is because she thinks she's a horrible person because of all this. Issei's reaction, in a word...
Real Life Writes the Plot: Characters can and will react to things that actually happen to the host site in real life, such as delayed comment notifications and paid account upgrades. In particular, Livejournal's infamous Release 88 and the game's subsequent move to Dreamwidth led to mass IC confusion.
The Axis Powers Hetalia cast is especially guilty of this, with numerous posts about world events being made. Especially funny was when there were national rivalries over who would win the World Cup and the most Olympic gold medals.
A Rare Sentence: Occasionally even the characters can't quite believe what they're saying.
Karen: It's a pleasure to meet you, Soifon-san, but Yoruichi-san says not to give you her pants. (new comment) And I find it disturbing that I have actually had occasion to type that sentence.
Resigned to the Call: Very few characters actually intended to join. Some like it once they're there, some never quite give up on leaving, but most seem to just sort of grudgingly accept it.
Retirony: You just knewPrim wasn't going to be saved from her canon death when she posted this:
Homura, Madoka, Nagisa, and Sherry— maybe when all this is over, we can have lunch again? Keeping in mind the good things that will happen in the future does a lot to keep us all going, and right now, I just keep thinking about that beautiful park on Nagisa's world. I'd love to go back there someday, all together.
Running Gag: It's common for newly-introduced characters to be warned not to put their name into search engines, do it anyway, and have their reactions to Rule 34 posted publicly.
Screw Destiny: For those who have learned of an impending death, the character in question and their friends try to stop it from happening.
Secret Identity: Everyone in the Gundam 00 cast gives out fake information as to where they're from and their professions... but Tieria takes it one step further. When he was in hiding on the Transformers world, he created an entirely new persona, Ila van der Aart, a female student at Mikaela's school. She still comes out to play from time to time, because you never know when an established alternate persona may come in handy.
Shipper on Deck: Three words: Mileina and Pearl. And the multiverse trembled in the face of their determination to pair everyone up. The two have even written anonymous collaboration fanfic (spelled and punctuated badly and with cliched plots for added hilarity) featuring their preferred pairings.
Stockholm Syndrome: Some of the older characters seem to display this for the community itself. They've been there so long and they know what the viruses are capable of doing, but something just keeps them coming back. For years.Lockon recently wondered why he kept coming back in a post on New Year's Eve, and Lyle listed this as the reason.
Story-Breaker Team-Up: One of the many ways the community threatens to take canon Off the Rails (and sometimes does). Even just the ability to worldhop is potentially a problem.
Tangled Family Tree: This one applies to the players as a number of them started acting as pseudo-family to one another to a point where siblings were parents to other siblings and... really, it's really justonebigmess.
Trigger: Some of the long-runners have been traumatized by things that left these. Azula (decapitation), Karen (kidnapping), Retasu (being referred to as "my dear"/"Midori"), and a few others come to mind.
Troll: There are always a few characters who revel in pissing everyone else off.
Turn Out Like His Father: During the What If? virus, Tieria and Motoko turned out like this when both of them ended up going Decepticon and joining their "father" (from another past virus), Blackout. Nasty stuff went down as they went to rejoin him.
Unconventional Formatting: Fun with fonts as detailed on the main Journal Roleplay page, and due to the internet-based premise you can assume the characters are deliberately using big font, sparkle text or whatnot.
Unpopular Popular Character: In-universe. Characters who aren't well-liked in their canons, such as Sena, generally aren't treated any worse than anybody else.
Unwanted Harem: Some characters just seem to collect people. Karen seems doomed to be the reigning champion, despite a series of challengers (most significantly Issei).
What the Hell, Hero?: An odd bit - Yuri is actually cheered by most of the comm after she steals Daiki Kaito's DienDriver after he ends up speeding up her universe's timeline by kidnapping the baby fairy Potpourri and giving it to his intended partner. The only ones who call her out on it are her castmates and she doesn't have a high opinion about them, so it didn't count for her. Only a little bit of guilt on doing so was real drive into getting her to give it back to him.
Eva-Beatrice: I know a few people that would say I'm a witch!
Kano: Maybe when they're trying to censor what they want to say in front of small children!
You Can't Fight Fate: A commonly-used plot device is worlds being temporarily sealed off, with communication (usually) possible but travel in and out impossible, to prevent outside interference in The Stations of the Canon. In particular, the Planetarian world in particular appears to be permanently closed, simply because allowing worldhopping would immediately lead to Reverie being swiftly removed.