Rosetta

Rosetta (ロゼッタ, Rozetta) is a mysterious character first introduced in the 1931: The Grand Punk Railroad manga adaptation by Ginyū Shijin.

Appearance
Rosetta has dark skin and blonde hair. She wears a sweater dress with a turtleneck, a scarf laced around her arms, and ankle boots.

Personality
Rosetta's most notable trait is her enigmatic nature. Though she at first seems to simply be Jacques-Rosé Boronial's more level-headed girlfriend, the occasional comment and aside glance suggest that she knows more than she's letting on. She also has a cheerful, flirtatious air to her.

Her true nature is that of a 'demon' like Ronny Schiatto, but her personality in that capacity has never been directly revealed.

Powers and Abilities
Rosetta has the ability to see the future. If she uses that knowledge to act in such a way that changes the future, her knowledge is updated automatically to reflect the changed future.

When she left the flask, she gave up a substantial portion of her ability to "interfere with the world"--perhaps to bend the laws of physics as Ronny does--but still retains at least a small portion of this, as she is seen teleporting weapons out of the hands of a Russo goon in 1931.

She may also be able to either turn back time or pass her knowledge of the future on to humans, depending on how one interprets the events of the 2006 manga.

Unknown
At some unknown time, possibly at the same time as Ronny (around 300 B.C.), Rosetta was created as a complete, omniscient and omnipotent homunculus sealed inside a bottle. In order to leave the bottle, she had to give up some of what made her complete; she chose to retain her ability to see the future and give up much of her ability to interfere with the world.

1931: The Grand Punk Railroad Vol. 1 (manga)
On the day of the Flying Pussyfoot's departure, Rosetta drives Jacques-Rosé to Chicago Union Station. She makes sure, as he gets out of the car, that he brings a wooden toy turtle with him. (This turtle toy will later stop a bullet and save his life.) In addition, she reminds him of his promise to take her to Dolce the next time he's in Chicago. He vows to return as soon as he's chastised the villains aboard the train and departs.

1931: The Grand Punk Railroad Vol. 2 (manga)
On the day of the Flying Pussyfoot's departure, Rosetta wakes Jacques-Rosé from what is taken to be a vivid dream about his journey on the Flying Pussyfoot. As he tries to explain that a kid named Czeslaw started talking about something immoral or important before suddenly stabbing him, Rosetta interrupts him by throwing his jacket at him and warning him that he'll miss the Flying Pussyfoot if he doesn't hurry up.

They leave for the train station, and Rosetta reminds him of his promise to take her to Dolce the next time he's in Chicago. When Jacques-Rosé makes his decision not to board the Flying Pussyfoot, Rosetta questions it, reminding him that he's been saying that the train reeks of evil. However, she expresses a private relief as he explains his reasoning, and when Jacques-Rosé muses about what Czes was trying to say, she correctly guesses that he was talking about Immortals.

Jacques-Rosé then involves himself in a conflict between a few members of the Russo Family and Neider Schasscule, to Rosetta's distress. While Jacques-Rosé is fighting the Russos, she takes the opportunity to tie up their guns. She then tries to plead with Jacques-Rosé not to fight for the sake of someone who showed up in his dream, whom he's never actually met. Jacques-Rosé answers that he knows his dream reflected reality and insists on continuing the fight, insisting that justice will prevail and thrusting his suitcase into Rosetta's hands so that he can protect Neider.

The Russo goon finally gets his gun free and takes aim at Jacques-Rosé, to Rosetta's obvious alarm and fury. She glares at the Russo goon, her eyes glowing, and just as he goes to pull the trigger he finds that his gun isn't in his hand anymore.

Neider then resolves the fight by shooting one of the Russos to protect Jacques-Rosé and leaving with the police escort. As Neider drives away, Rosetta asks what she and Jacques-Rosé should do now; under her breath, she remarks that she's tired from using her power too much. Jacques-Rosé suggests a trip to Dolce, and she agrees.

1931: Another Junk Railroad
Jacques-Rosé and Rosetta make a small cameo in Another Junk Railroad, when Fermet overhears Jacques-Rosé's decision not to get on board the Flying Pussyfoot despite having splurged on a second-class ticket. Fermet, who intends to stow away, then decides to hide out in what would have been Jacques-Rosé's cabin. He takes no further interest in the pair.

2003 (as appearing in 1935-A Deep Marble)
Somewhere in the world, during a certain month of 2003, Rosetta approaches Ronny Schiatto for conversation. He expresses ambivalence over whether he should be greeting her in the style of a reunion or of meeting her for the first time and questions whether their meeting might be something she deliberately engineered. She then inquires about the events of 1935: how it began, and who might be considered the main character. Before answering her question, Ronny notes her regret over not being able to see all the incident since she avoided taking part in it. He points out that in order to leave the bottle, they had to make a choice and become incomplete; whereas he chose the world, she chose the future. He suggests that if she is now bored as a result of her choice, she can enjoy the events of places her power can't reach through television and newspapers and the like. Though her responses aren't recorded in the chapter, Ronny's dialogue implies that his suggestions are not warmly received.

Finally, Ronny's settles on starting the story of 1935 with Firo, though Rosetta is not very familiar with him (or, for that matter, with Isaac and Miria). She questions his impartiality, but he easily admits to being partial and begins his tale.

Trivia

 * Rosetta's teleportation of the Russos' guns closely parallels Ronny's teleportation of Maria's katanas and Adele's spear in 1933: (First) The Slash ~Cloudy to Rainy~. The similarity is highlighted in the bonus comic that ends the second volume of the manga and specifically pointed at as a hint to her true nature.
 * Rosetta's choice, to keep her knowledge of the future at the expense of an omnipotent ability to affect the world, seems to be more common among homunculi than the reverse; several other (unnamed) homunculi have chosen that trade-off, leaving Ronny as the only one to retain his ability to affect the world at the expense of the ability to know the future.
 * The conversation Fermet overhears about Jacques-Rosé's decision not to board does not match the conversation that appears in the manga.