Characters that appear in multiple games in the Disgaea series:
It's a prinny, dood.
Not actually a character per se, but still deserving of mention. Prinnies are exploding demon penguins who talk like Surfer Doods which serve as the primary labor force of the Netherworld (Though they exist in Celestia as well and are treated better there). Etna keeps a squadron of Prinnies with her at all times. In fandom, they have been upheld by fans as the unofficial mascots of the franchise, a position since adopted by the developers, leading to their own spinoff game. All Prinnies contain the souls of sinners and criminals and, as such, are designated by the Powers That Be as the Butt Monkeys of the universe.
The Atoner: Prinnies are the souls of dead sinners trapped in penguin suits, and must work at the Netherworld and Celestia to repent and be reincarnated. In Celestia they must do good deeds (usually cleaning and housework) while in the Netherworlds they do menial tasks (cheap labor and soldiers) for low pay in order to earn enough money to literally pay off their karmic debt.
Death of a Thousand Cuts: Their standard attack is slicing at the opponent multiple times for multiple hits. Because of this, they don't always do very much damage to the opponent unless properly leveled and equipped.
The Ditz: With some exceptions, Prinnies seem to lose a lot of IQ points upon becoming one. Disgaea 4 all but outright states that Prinny training is what breaks them down from whatever they were into this.
Furry Confusion: The general behavior in regards to ghosts and Prinnies in Trinity Universe is much like this. Despite being essentially ghosts themselves Prinnies treated fairly normally while non-Prinny ghosts like Pamela are treated as terrifying even, and especially, by the Prinnies themselves.
The Goomba: When you face them as enemies early game, though you do encounter some high level ones as well.
Note that even the high level one, generally, can be thrown. And explode.
Immortal Life Is Cheap: Since "reviving" a prinny involves little more than stuffing them into a new prinny suit, it's impossibly cheap (1 HL) to bring back even the strongest prinny — which is partly why their bosses have no issue with abusing them to their hearts content.
Killer Rabbit: They're certainly not the most powerful monsters in the game, but like all Disgaea characters you can level/equip/reincarnate one into a wrecking machine. Watching an adorable penguin slice monstrous demons to ribbons is always good for a laugh.
Lazy Bum: It's implied that most Prinnies become this if left on their own, thus why their masters are usually very strict.
Made of Explodium: Their human souls, combined with cheap crafted bodies, means Prinnies are highly unstable. Sufficiently jarring impacts cause them to explode. On the downside, this means you can't toss them around the grid for fine unit positioning, which is normally a useful tactic. On the upside, they make great impromptu weapons!
It's gotten kind of confusing now. The side-stories in D3:Ao D have Prinnies with a different VA (Sam Riegel) and Disgaea 4 has yet another different VA for them. Some fans may like this as it gives Prinnies different sounding voices across the games but some fans will still desire consistency.
If you lose to Prinny Baal in Makai Kingdom, he leads the prinnies to conquer the universe and become the dominant species.
The Bonus Boss, Baal first appeared as a Demon Lord in La Pucelle. He Took a Level in Badass in Disgaea 1 where he became known as Supreme Overlord (or "Tyrant") and was the one who was ultimately responsible for King Krichevskoy's death; it was propaganda that blamed "black pretzels." In this game, he became a Prinny after his first defeat; it was assumed at the time that this was a reincarnation. Baal appears again in Phantom Brave, this time taking the form of a Mushroom-esque monster, an Eringer/Funguy. It was assumed at the time that he had gone through his reincarnation period as a Prinny, yet retained his incredible strength. More of his true nature became known in Makai Kingdom, Baal does not die when his body is killed, rather he merely finds other host bodies to inhabit and he is as old as the universe itself.. This became worse in Disgaea 2 when he started getting more than one body. In Disgaea 3, Baal has more of a storyline, he is stealing traits from various characters for some unfathomable reason. Expect lots and lots of Level Grinding to be anywhere near capable of fighting Baal, his HP tends to be in the millions.Notably, Baal was absent from Zettai Hero Kaizou Keikaku; in fact, Valvoga's description states that he conned Baal out of theBonus Boss position. Nevertheless, Baal's made his appearance as a Bonus Boss in Prinny 2 and returns as a DLC Bonus Boss in Disgaea 4 and Disgaea D2: A Brighter Darkness.
Ambidextrous Sprite: Applies to all of the games sprites of course, but is especially noticeable on Baal, whose cape constantly switches the fist it's covering with as much as a tilt of the camera.
Scarily enough, he's not the hardest example; really, beating Baal is a trial in level grinding and patience to get your stats high enough to kill him in one round.
Bragging Rights Reward: Beating him usually results in little beyond a title change to Lord of Terror. Of course, if you did actually get anything from beating him, it'd be rendered useless simply on the basis that you already just beat the one guy literally one thousand times more powerful than anything outside of a Nippon Ichi game ever.
In order to justify this, there is usually a stronger version of Baal lurking somewhere in the game.
Also, each game has a set of "Stronger Enemies" and "Weaker Enemies" bills you can use to make him tougher, along with the rest of the game...
Characterization Marches On: Essentially a Flat Character that never even spoke in his early appearances, he has more recently been given SOME personality in that despite being an absurdly powerful demon, he apparently needs money.
From Bad to Worse: If you lose to Prinny Baal in Makai Kingdom, he'll go on to conquer the other netherworlds and make prinnies the dominant species and rulers of the universe.
Galactic Conqueror: He's state to have conquered every Netherworld he come across before coming to Krichevskoy's netherworld. If you lose to him in Makai Kingdom, he goes on to conquer the entire universe.
Impossible Thief: A plot in Disgaea 3 revolves around everyone gunning for him, outraged that he stole things such as Mao's "precious item", Flonne's commemorative DVD Box set, Laharl's height and screen time, Marona's innocent and pure heart, and the second "A" and space in Master Big Star's name. In the end, it turns out he didn't actually steal anything to begin with.
Joker Immunity: Despite his numerous appearances, he never seems to die. Makai Kingdom states he's an aggregate of evil souls, and that any time he's defeated, he'll just find another body and come back later.
Killer Rabbit: Not always, but always taken to the logical extreme when he is. Level 9999^23 prinny, anyone?
His Eringa form in Disgaea 3 screamed Killer Rabbit with its cutesy voice and lovable shroomy exterior. But as soon as the party checks his level...
Marathon Boss: Depending on the game and stats of the player's party, Baal can turn out to be this, but his Disgaea D2 incarnation takes the cake. Among the few who have beaten him, even fewer have done it in under 30 minutes.
Me's a Crowd: Some fights with him have more than one of him around. In Disgaea3, this works with an Evility that makes him/them immune to one attack or skill used him for every Baal present, meaning he has to be hit repeatedly to hurt him.
Multiversal Conqueror: And Laharl's Netherworld was next on his list. He was stopped by Krichevskoy giving up his life to seal him away.
Non-Standard Game Over: Some outcomes of battle with him end like this. If Laharl is the party leader in Makai Kingdom, then even if you defeat Baal, Laharl will destroy the body Baal's inhabiting (which, naturally, belongs to Zetta), leading to a game over.
Took a Level in Badass: When it looked like Pringer X was going to phase him out as the premier Bonus Boss, he returns in Disgaea 4 with a vengeance, now far outstripping Pringer X in power and packing Evilities that make killing him an outright marathon. Disgaea D2 makes his stats even more insane, gives him a version of Pringer X's evility Special Skill Solved, along with a number of other nasty tricks.
Villains Out Shopping: His DLC appearances in Disgaea 3 and Disgaea 4 has him showing up for job interviews. In the former, Almaz guesses that even Tyrants need work.
When All You Have Is a Hammer: In all his appearances, his attacks all consist of summoning giant swords, sum of which are as big or bigger than he is, and don't have any fancy effects. Thing is, these hurt, ALOT, in Disgaea 4 his standard attack can one-shot a level 9999 character.
It Only Works Once: His evility, Special Skill Solved, makes it so that any special move used on Pringer X in a battle cannot be used a second time for any damage. This includes when there are multiple bodies. (The immunity is then given to all of them.)
Killer Rabbit: His size has varied from game to game, but Disgaea 4 has him even smaller than a regular Prinny. He'll still wipe the floor with your entire party, though.
Lethal Joke Character: A robot prinny doesn't look like much, but this thing is damn powerful, and requires a bit more strategy to beat than most other Disgaea BonusBosses due to his evility.
Stupid Wiki! Couldn't even find a good image of me!
The intended heroine of Nippon Ichi's next game following Makai Kingdom, Asagi's game was dropped after Zetta defeated her and she has become a vagrant Bonus Boss in all Nippon Ichi games since, wandering from game to game in the attempt of plugging her own disowned game or trying to commit hostile takeovers to put herself in the main character spot.
The Apprentice: Valvatorez makes her his "Prinny Instructor-In-Training" after defeating her in Disgaea 4.
Arch-Enemy: Zetta to Asagi and for good reason — It's his fault she's stuck as the wandering protagonist to begin with. When they finally meet again in the Netherbattle Tournament, she gives him an ear full.
Determinator: She's tried how many times to get her own game already? And she shows no sign of slowing down.
Died Standing Up: In Prinny Can I Really Be the Hero, after her final defeat. She was so determined to become the main character that she just refused to yield ! In the words of the Hero Prinny : "That's dedication, dood !"
Don't You Dare Pity Me!: In Disgaea 4 Valvatorez actually offers her the position of main character because she's just so pathetic. Asagi refuses his offer for this reason and insists on fighting him for the role of main character.
Asagi: I don't need your pity! Ahh, come on, knock it off! Stop looking at me with those pitiful pitying eyes!
High Definition: Subverted and lampshaded in the fourth game, in which she's the only character to retain her old sprite, making her look laughably out of date compared to the rest of the cast. She apparently "missed the memo."
You can give her a high def sprite through DLC, but still.
Asagi: I don't think it's right to discriminate based on appearances. I'm just a little lower resolution, that's all!
Hostile Show Takeover: She figures if she can beat the main characters of the various games, she'll prove herself worthy of being a main character. Unfortunately, the inverse also holds - if she's gotten beaten seven times by a Prinny...
While she drops trying to become the main character in Disgaea D2, she is still trying to play the trope straight by trying to hijack Lanzarote's concert- though she arrives on the scene late. She also plans on offing Laharl so that she can become the Overlord.
Idol Singer: What she becomes at the end of Prinny 2. She claims she is one in Disgaea Dimension 2, but turns out she didn't even debut or even audition and was planning to hijack the concert of the current Idol Singer, Lanzarote.
Me's a Crowd: Her appearances in Cladun and Disgaea 4 (as HD Asagi) make it clear there are multiple Asagis running around...somehow.
Non-Standard Character Design: Happens to her in Disgaea 4. That game uses HD sprites by default, but Asagi doesn't have one, and looks decidedly odd next to the other characters. An HD Asagi is free DLC, however.
Also in Disgaea 2, where she retained her original sprite from Makai Kingdom, causing her to look distinctly chibi-ish compared to everyone else in the game. Both cases are lampshaded to hell and back.
Takehito "Haradaya" Harada's mascot, she first appears in the first game as a guide to the Dark Assembly (and in the remakes, a very broken recruitable character), and then returns in the second game to take over Etna's role of providing "previews" of the next chapter, in the form of a news broadcast. Accompanied by her rabbit, Usagi, who is also her emergency food source. Usagi's the one who actually does all of the talking.
Beware the Nice Ones: Moreso in art that may or may not be canon. While it's by the original artist, but doesn't quite fit with the canon, although eating Usagi isn't exactly very nice.
When recruited as DLC in Disgaea 3, Mao is scared of her or rather her legion of fans.
As is Adell when recruited as DLC in the Updated Re-release of Disgaea 2. She is considered in the game as invincible as simply touching her would enrage the fanbase.
Adell also appears to be a member of the fanbase.
In the Disgaea 2 manga, after leaving Laharl's employ after the fiasco with Etna, she's seen working at Netherworld City Hall, where Etna heads to try and get a title change to Overlord. When the title switch fails due to her not meeting any criteria, Etna contemplates trying to blackmail Pleinair, and we get this gem, which gets Etna to back down very quickly:
Pleinair: How would you like to die socially? I'll delete you from all public records.
Cute Mute: She actually did get a voice in her DLC in Disgaea 3 and Disgaea 4, but it's incredibly low. You'll have to turn off the BGM just to hear it.
Game Breaker: invoked She has incredibly high dodging and hitting numbers. The latter also goes well with her high gun skills (since their damage is calculated by hit stats more than attack stats).
On the Next: In Disgaea 2. Usagi does all the talking, temporarily replaced by Axel after apparently she eats one of her Usagi, then when she's left alone due to Axel running off to save the day, in true Cute Mute form, :she acts like she's reporting on the next chapter, visual aids and all, but doesn't say anything.
The Other Darrin: Their voice actors are constantly changing. It's actually explained in-universe in Disgaea Infinite that the Prism Rangers often die and the producers search for or kidnap possible candidates.
Red Is Heroic: Played with. While Prism Red is the leader of the team and gets the most appearances and lines, he is also usually the most pathetic of the team as he is the only one always actively looking for friends.
Running Gag: That's not enough colors for a rainbow! They also have no friends!