I couldn't miss the chance to practice my drawing!
Rostnsthal the Reborn is a non-playable character in Final Fantasy XIV. Originally known as Sthalmann, he was the Commodore of the Knights of the Barracudas circa 1562 of the Sixth Astral Era, until his actions led to him being disgraced and changing his name. He reappears in Heavensward as a marksmanship instructor in the Machinist job quests.
In 1562 of the Sixth Astral Era, a mysterious islet called Seal Rock suddenly appeared in the Rhotano Sea, admist a flurry of speculation in the thallocracy that it was the mythical Swallowtail Roam. At the time, Sthallman was the Commodore of the Knights of the Barracudas, with ambitions of taking the Admiral's seat. Sthallman had recruited allies promising them power when he becomes Admiral of the city-state.
One of them was Emerick of the Kraken's Arms, who had ties to the Serpent Reavers. Another was Merodaulyn, one of the few male members of the Sanguine Sirens, who was placed in the 5th Levy Seal Rock Provisional Unit. The plans was to have Emerick hand a Navy sailing chart to the Serpent Reaver Travanchet, who would pass it to the Sahagin. Merodaulyn would ensure the 5th Levy would fail in the inevitable attack, allowing Carvallain and his Kraken's Arms to land on the isle itself. Under Sthallman's orders, Emerick procured a curious horn-shaped artifact.
Carvellain turned in Emerick to Sthalmann after learning his role in the sahagin attack, whom took him in his protection. With other pirates seeking blood, Sthalmann tricked the Sanguine Sirens into attacking Mealvaan's Gate, and used the fallout to confiscate another artifact from the Seal Rock: a stone tablet with inscriptions in Rhotano Bloodcant.
Merodaulyn later freed Emerick, and the two planned an escape. Just as Y'shtola warned them that "the shadoweaters" were after the artifacts and respected they turn them over, Travanchet revealed his true nature as one of the aforementioned shadoweaters by attacking their ship. Two other Barracuda warships, themselves keeping tabs on Y'shtola per Sthalmann's orders, tried to attack Trevanchet's vessels. The standoff was interrupted by a large sea serpent that emerged from the water, damaging the ships with a wave.
The tablet would be lost at sea, and with Emerick and Merodaulyn escaping Sthalmann lost an opportunity to dismantle two of the largest pirate gangs in Limsa Lominsa. He later orchestrated a plan to to assassinate the then Admiral, and went to Gods' Grip in hopes of activating the power of the horn. He would be confronted by Y'shtola, who demanded he hand it over to Sharlayan. Undeterred, he threatened to kill her if she didn't tell him how to use the horn. This scene would be seen in an Echo vision by the adventurer ten years later, who saw Emerick's memories. Suddenly, the horn began glowing, and at that moment a starshower erupted in the sky, with Trevanchet appearing from a nearby meteorite impact. He appeared behind Sthalmann and seized the horn, declaring that "power as this does not belong in the hands of your kind."
Since then, Sthalmann was disgraced for his plot, and became a drunken pirate captain of a crew of one, and changed his name to Rostnsthal. His former second-in-command, Reyner, become the new Commodore, a position he retains to present day. The chair of Admiral would eventually be passed to Merlwyb Bloefhiswyn.
Rostnsthal would not be seen again during the Seventh Umbral Era story arc or A Realm Reborn.
Five years after the Calamity, Rostnsthal was hired by Stephanivien as a marksmanship instructor at Skysteel Manufactory. He trained House Haillenarte's maidservant Joye and other volunteers in firearms as per the concept of the machinist. Just as the Warrior of Light arrives to sign-up as a machinist, Rostnsthal seemingly resigned his post and left for Camp Overlook. After some pleading by Stephanivien, Rostnsthal reluctantly agrees to test the adventurer's worth, and sets up an impromptu training course in Outer La Noscea. Satisfied with the Warrior of Light's potential, he agrees to return to the manufactory.
Throughout the questline, he discovers suspicious individuals attempting to harass or sabotage the manufactory. He suspects his own past reputation may be to blame, though Tedalgrinche shows to be mostly focused on discrediting Stephanivien. Rostnsthal otherwise does not participate in the manufactory's battles, typically just giving advice as pper his contract.
In the MCH58 quest "Taking the Fall," Rostnsthal tries to turn himself in on the insurrection charges levied against the manufactory, against Stephanivien's wishes. After getting an essential weapon upgrade ready, he and the Warrior of Light to try to talk Rostnsthal out of it in the quest "Rusted Steel." He eventually calms down, and confesses to his treacherous deeds in the past, and his regret over betraying his subordinates. He asks to aid his students in the upcoming trial by combat against Veri Seren in order to atone for his actions as Commodore.
Once Veri Seren is slain and the Skysteel Manufactory is exonerated from Tedalgrinche's charges, Rostnsthal decides to take his leave, nominating Joye as master marksman.