Rozalin - Game Progression
Here I go into Rozalin's story in detail as presented by the game.
The Overlord's Daughter
Rozalin's story begins when Disgaea 2's does. When Adell's mother finally had all of the preprarations made, preparations that took her fifteen years to do, and she was ready for the summoning ritual. In the name of Adell, she was ready to summon Overlord Zenon.
Well, what do we have here?
Apparently, something was odd. Here they were expecting a huge scary man, yet here they have a cute young girl with a big chest in a nice dress who has no experience in battle whatsoever. Could this really be the feared God of All Overlords who slayed over a thousand Overlords, ninety-nine in one day before they fled to Veldime?
Wait, if you know the spoiler, don't answer that.
No, the girl, named Rozalin, is adamant that Overlord Zenon is her father by way of quite sternly stating that she is his one and only daughter. Quite the pompous and haughty demeanor in possession, Rozalin goes on to ridicule Adell. However, it isn't until long that Rozalin realizes that she is tied to Adell because of the summoning ritual. Stupid summoning rituals. They're worse than marriage.
So, Adell and Roslin are now off to try to look for Overlord Zenon. Adell instructs Rozalin on how to fight, and Rozalin gets the oh-so-bright idea to off Adell so she isn't restricted by the ritual contract. Unfortunately, not all demons in Veldime work for her father, it seems; the prinnies attacked her, instead. That was one thing wrong. The next thing is that when she tried to trick Adell into fighting Axel under the belief the Axel was her father, Axel was defeated. Oopsies. I hope Adell's fists didn't leave too big of a mark.
Rozalin the Liar
Despite Rozalin's atempts to off Adell as well as crappy attempts at lying, Adell once again sets out with Rozalin in tow, trusting her. Y'know, because it's his style. As much of his style as that giant oversized ugly red tie he's permanently part of his wardrobe. But I digress.
Well, lo and behold, luck abounds! The dynamic duo encounters the ruined remains of a castle! Rozalin uses this opportunity to skillfully bide for time as she and Adell explore these ruins, which she claims to be Zenon's Palace. To further cement her argument, by more luck they stumble upon her childhood friend, the faux-french-accented frog Tink! Well, both he and Rozalin claim that he wasn't always a frog. He claims that a terrible raging Overlord from another dimension cast a curse on him or something like that.
Well, after getting him back to normal from his pervy-state, Tink tinkles his way into your party, and the party runs into Axel again, who's intent on getting revenge on Adell and co. for beating him up on interdimensional television. Now the company thinks he's dead, much like his career. So, he decides to try to attack, and take Rozalin hostage as Rozalin really does suck at hiding her identity and keeping herself inconspicuous. There's a reason your father locked you away from the public eye, sweetie.
Anyway, the group defeats Axel, and gets pissed that Zenon is once again unfound. They head back to Adell's house for some good times.
Rise of the Beauty Queen
Tink and Rozalin come up with the brilliant idea to get rid of Adell (thus nullifying the contract) by taking him to a really dangerous place... so, they decide to take him to some swamp known for really big, ugly, and powerful monsters.
Well, after a few uneventful monster encounters, the duo faces off a very familiar face for those who've played the original Disgaea: Hour of Darkness. It's Etna, now a Beauty Queen, sporting a new wardrobe, and without Laharl and Flonne?! Unfortunately, Rozalin manages to piss Etna off by mentioning her washboard chest (which is kinda odd, considering Etna's age). Etna, with her army of Prinnies, attacks!
The group, obviously outmatched since Etna was most likely powerleveling from the previous game (oh those crazy side quests), faced defeat. Since we've already established that Rozalin truly sucks balls at concealing her identity, Etna demands that Rozalin take her to Overlord Zenon so that she may become an Overlord herself. The only problem?
Rozalin finally admits that she's never even met her father!
Axel's Scheme
Rozalin wonders why Adell is forfeiting his justified right to make her stare at the business end of a hissy fit. Adell just trusts her anyway. Anyway, rather than letting the game go into the direction of mushiness, what the two find out is that Axel is up to his no-good tricks again. This time, the former Dark Hero has decided to kidnap Taro and Hanako! Oh noes!
So, Adell, Rozalin, and Tink make their way to some river whose name I forget, they fight a bunch of monsters, talk a bit, and finally face Axel. Turns out it was another one of Axel's attention-needy schemes to get the networks to affirm his not-dead state once more. Adell and the others beat the crap out of him once again, and while Hanako is saved, Taro falls into the river.
Looks like the rescue isn't done yet!
The Promise
After some more filler (and Hanako is glad this all happened so she can at least get out of the house), the group enters a cavern to save Taro. Unfortunately, not only are there powerful monsters, Zenon's servants are also there! And if that wasn't enough, Axel is also causing trouble...
Basically, one of Zenon's servants decides to pretend not to find Rozalin and her entourage, and also gives them a magic flute which should soothe the nasty little beasts into submission. However, after a failed attempt, Rozalin explains that flute-playing was one of her many talents, as was fit for the only daughter of Overlord Zenon. Hanako, however, decides to tease her by saying that since Adell's lips touched the flute first, her playing the flute would be like an indirect kiss. This prompts Rozalin to get flustered and toss the grimy, disgusting flute away. Oops. Nice going, Rozalin.
Anyway, later when they save Taro only to be surrounded by the blasted beasts, Axel appears and unwittedly saves the day by playing the flute. All's well that ends well, and Taro is now Rozalin's servant for good. After all, Rozalin helps save Taro because a good mistress takes care of her servants.
Coliseum
Hmm, looks like Overlord Zenon is holding a battle tournament, and the winners get to meet him! What an opportunity! Adell and the others enter. They also meet Etna, who's also planning on entering the batle tournament at her chance to claim the title of Overlord for herself to shove into the face of Laharl back at home.
Interestingly enough, a smidgen of Adell's past is vaguely alluded to from a succubus. Although it isn't known exactly what transpired between them, Adell states that it's because of her he doens't like girls and she's the reason he has the scars on his face. (I personally think the latter point is kinda cool.)
Then, they also meet Yukimaru. Yukimaru mentions that the sparkle in Rozalin's eyes could only be from one of the Snow Melody Clan. Rozalin mentions that it's possible that her mother was from the Snow Melody Clan...
Battle Tournament
First off, someone who looks like Yukimaru but acts nothing like Yukimaru attacks Rozalin! Then, the Prism Rangers (who are, as Rozalin notes, not even filled with all seven colors of a rainbow prism), and in the semi-finals they face off Yukimaru and other shinobi and kunoichi.
Then Axel decides that in order to get more attention, he uses his referee powers of the whoa to face off against Adell and company in the finals. Fortunately, he is easily taken care of and the party gets to meet Overlord Zenon.
Zenon Appears!
Well, turns out that Rozalin stands up for her friends. Unfortunately, Zenon's not buying it. However, Etna is here to save the day, and distracts Overlord Zenon (all her powerlevelling pays off!). The group manages to escape. Rozalin, understandably, is depressed; her first face-to-face meeting with her father resulted in him seemingly not caring about her or her views; he instead was about to erase her memories.
Summoned Overlord
Since meeting Overlord Zenon proved to be an odd occurrence, the group ponders this. Etna reportedly killed Overlord Zenon, but her title didn't change! How odd... After Etna left, the group rethinks their strategy. They come up with the idea of instead of summoning specifically Overlord Zenon, they could try to summon "the strongest Overlord in Veldime". That would be sure to summon Overlord Zenon, if indeed the one they met before was a fake.
The only ingredient they were missing was a powerful demon's nail clipping. Shoot, Etna already left. Time to chase after her.
After more filler battles, they finally meet Etna. They fight her prinnies to get her to agree to give them a nail... and she does. Only, she doesn't give them her nail. Oops.
As a result, when the summoning is done, Etna is the one summoned. Not only that, because Etna gave them a crappy subtitute for her nail clipping, her summoning was botched and she's now back at Level 01. Oops.
The Two Ninja
The group sets out to find Fubuki. Somehow the group meets Zenon again, but this time Yukimaru's brother, Fubuki, appears and performs Midare Fubuki on Zenon. Zenon is once again "defeated", but Fubuki is in bad shape.
Castle Raid
Remember that old fart from the battle tournament? He mentioned that he was from Shinra Tower, and Shinra Tower has a buttload of herbs. Those herbs could help Fubuki!
Filler, filler... ooh, look, it's Laharl! Laharl, much like Etna, beats the crap out of the party, and Rozalin shows off her Seal of the Four-Leafed Clover. Well, Laharl decides to be a prick and break it.
Very, very bad idea.
Now, Laharl isn't known for making good decisions in the first place, but this one was terrible.
What's this? Rozalin transforms! And it's not like a mahou shoujo transformation where she holds up a glitter pen and she's in a short skirt, either. In fact, she becomes mega-powerful, stating that she's a "being of solitude", and proceeds to whup Laharl's butt and spank him into tomorrow. Thankfully, Rozalin soons snaps out of it once the Seal of the Four-Leaf Clover is restored. But... what was that?
The Truth
Fubuki got better despite Laharl eating all of the yummy herbs (unfortunately, Etna did not regain her levels as she planned).
The party then proceeds to enter Overlord Zenon's Castle, since he's an imposter and decides to bring justice to all.
So, the party fights more battles in this final, climatic chapter. The Dark Hero decides to help them by distracting the enemies. Fubuki helps and teaches Yukimaru the Midare Fubuki. And Zenon's Servants are hinted at being Adell's true parents (thus explaining why Adell never turned into a demon... because he was a demon to begin with). Finally, the group faces Zenon.
The current Zenon was revealed to not be the real Zenon. Instead, this Zenon was an Overlord defeated by the true Zenon. He tracked Zenon down to Veldime, who was reincarnated to the Snow Melody Clan, thus explaining their obliteration. He then proceeded to keep Zenon, now called Rozalin, helpless in a manor as he took this twisted revenge on her. However, his special ability was to absorb the human consciences of humans, and convert that to his own power; that is why he hasn't died yet. That is why Veldime became the way it is.
He was too powerful, and he was desperate; soon, there would be no human consciousness left for the process to be reversed. Rozalin wished for power to save her friends, and willingly summoned the Zenon within her to finally defeat the fake Zenon.
However, Zenon was not turning back into Rozalin. She was intent on destroying even her friends, as the personality of "Rozalin" was nothing more than the puppet she escaped into during her reincarnation. She was tired of the bloodshed, but bloodshed kept on coming to her.
And, Adell made it all better by giving her a kiss.
On that note, Rozalin awoke, and there was a happy ending. Tink was even turned back into the bloody Frenchman he was.