In the beginning, Etna tries to wake up Laharl
by trying many things, from drills and flails to Gatling guns, swords
and jackhammers. From then on, Etna becomes Laharl's closest vassal, though not necessarily most trustworthy vassal, aiding him in his rise to power. She is the only vassal from Laharl's original servants who goes out on the battlefield for him.
Etna is mostly carefree, but also very devious. Its often hard to tell who she is really working for. She has holds deep respect and loyalty towards Laharl's father, King Krichevskoy. She is known for ending an episode with a "preview" to the next episode, where she has the starring role, the previews are often parodies of famous TV shows, anime, or video games with the other characters making side comments.
In all but the 'Flonne Tragedy', 'Good', and 'Human Conqueror' ending, Laharl gives up his position as Overlord to Etna. In one ending, she even murders Laharl and Flonne
to get the throne, while in the anime, she is given the position of Overlord
after Laharl decides to sacrifice his life for Flonne.
In the PSP
ports of Disgaea: Hour of Darkness, there is an alternate mode in the game called Etna Mode. In this mode, rather than awakening Laharl, Etna accidentally kills him and sets out to reclaim her memories while tricking the Netherworld into believing that Laharl is alive by attaching an antenna on a Prinny's head, claiming it to be the demon prince. The alternate mode goes into Etna's past as a commoner before taking in by Krichevskoy. As a commoner, she was often shunned by most noble demons, though a dog-like demon often kept her company as a sort of pet. The pet is later killed by noble demons at which point Krichevskoy helps the young Etna bury it and offers to take her in, stating that commoners should not bear harsh treatment due to any differences. The scene is a big reason for her devotion to the King and backs up much of her diary entries.
At the end of 'Etna Mode', it is hinted that Etna may have some form of affection for Laharl (She was seen deeply regreting her betrayal and crying to herself over her kiilling of the prince, and offering him a small prayer for his 'peace and eternal rest'.)
Etna quits her position as Laharl's vassal after a fight with Laharl over pudding (which is supposedly a rare delicacy from the Sea of Gehenna) and becomes a Demon Lord, taking the Prinny
Squad with her. She then travels to Veldime, hoping to eliminate Overlord Zenon, the God of All Overlords, and runs into Adell
and his party in the process. In Episode 9, she gives Adell a fake 'Demon Lord's Nail' and is accidentally summoned by his mother. The failed summon drops her back to level one, and in order to regain her former power she deigns to join up with the player's party. At the end of the game, she, along with Hanako
, returns to the Overlord's Castle as Laharl's vassal once again.
Etna appears alongside Laharl and Flonne and assumes the legendary Overlord they are looking for is Mao
, while Mao and his party believe that Laharl is the legendary Overlord. After the battle, she tries to push Laharl to defeat Mao as the two are evenly matched until Almaz makes them realize that neither of them are the legendary Overlord. After the battle, Etna joins the party. Like many of the characters, she has lost something to the legendary Overlord: her one billion Hell savings account.
In an alternate battle, when Laharl appears before Mao, claiming to be his father, Etna tries to convince Mao that she is his mother, speaking in a motherly tone. However, when Flonne starts claiming she's his mother, the two begin to argue over who the mother should be. Her description of Laharl's selfishness makes it clear that she still doesn't forgive him for eating her pudding and that he still eats her sweets without permission. However, in the end, Laharl reveals that they really weren't his parents after all, just an Overlord and his vassals passing by.
She sends off her Prinny Squad to get her the Ultra Dessert. She gives her Prinnies a special red scarf in order to prevent them from accidentally exploding. She can also be fought in an extra battle when the Prinnies decide to revolt. However, she does not actually engage them in battle, but has Pringer X, small Prinny robots that hover and shoot lasers, fight them while sitting on top of a throne carried by four Prinnies. Occassionally, she will call either Flonne, Aramis, or Gordon, Jennifer, and Thursday when Pringer X is defeated.
Etna also appears in both Makai Kingdom
& Phantom Brave
as an extra boss. In Phantom Brave, she is the reason why Laharl was sent to Ivoire in a bottlemail. Upon hearing that Laharl had been defeated by Ash and Marona, she and Flonne battle them, but fails to defeat them. She and Flonne later return alongside Laharl to fight them again. In Makai Kingdom, she introduces herself to Zetta in a next episode skit and then returns to fight alongside Laharl when she is defeated. She also appears as one of two Nippon Ichi
characters in the game Cross Edge
(The other being one of her Prinnies) , as well in the Demon Dog King story in Trinity Universe