Duke Cayenne is a noble whose lineage extends back to the days of the War of the Lions. Due to being a member of one of the Four Great Houses in Erebonia, he controls the province of Lamarre and all of its resources. He is also the ruler of the Port City of Ordis.
Cayenne controls a great deal of resources and is the main backer and Supreme Leader of the Noble Alliance. He secretly arranged for the construction of the Pantagruel and was the starter of the Erebonian Civil War.
He also took in a young Crow Armbrust after he had lost his grandfather and backed him in his pursuit for revenge against Giliath Osborne, bankrolling the foundation of the terrorist group Imperial Liberation Front.
Duke Cayenne is a true aristocrat. He loves extravagance and flashy clothes, but hates the idea of commoners getting into positions of power which is why he hates the Reformists. He also acts condescending towards others.
“A man's worth is decided not by himself, but by those he rubs elbows with.”Cayenne also thinks that people should bow to him because of his noble lineage. He feels that his family has been robbed because of what happened to his ancestor Orthros Reise Arnor during the War of the Lions. His main goal in seeking the Divine Knight Testa-Rossa is to reclaim Erebonia and return it to the days when nobles ruled and commoners lived to serve the nobles.
— Duke Cayenne, Trails of Cold Steel, Chapter 5.
He is also not a fighter and prefers to make others do the work for him. He carries an immense hatred for Giliath Osborne who he sees as being an obstacle.
Growing Tensions - S.1204 -
In Trails of Cold Steel, Duke Cayenne is introduced as a minor character who only officially appears during the Legram Field Trip Arc. But, behind the scenes, he is the one who backs the Liberation Front, helps plot the assassination of Giliath Osborne and initiates the Erebonian Civil War.
Duke Cayenne is first introduced having a meeting with Victor S. Arseid in Victor's home about joining his Noble Alliance against the Reformists with Xeno and Leonidas acting as his bodyguards. Prior to this, he is just mentioned as being a member of one of the Four Great Noble Houses.
During his conversation with Victor, he tries to coerce him into joining the Alliance, but Victor humbly refuses. He also advises him against causing him trouble and doing stuff like training the Imperial Army. He then bids Victor farewell. As he heads down the staircase, he comes across Rean Schwarzer and the rest of the field trip group. Seeing Laura and Jusis, Cayenne addresses the two of them. After a brief silence, Duke Cayenne laments that he can't stay and talk with them and states his hopes for arranging a meeting with them in the future. He then leaves Legram in a car with Rufus Albarea.
After the encounter with Duke Cayenne, Victor explains to Rean and co. that Duke Cayenne and his Noble Alliance have begun moving in secret. He explains that they have been secretly gathering countless times to reaffirm their unity against the Reformists. He also explains that Cayenne has been trying to gather all of the other neutral lords and barons including himself into joining their alliance through a show of coercion and force.
Erebonian Civil War - S.1204 - S.1205
Duke Cayenne first officially appears towards the end of Act 1 making an official statement from the Pantagruel after he attacks Ymir. Prior to this though he is only really mentioned in the Imperial Chronicle as having taken control of Heimdallr and leading the Noble Alliance to victory against the Reformists.
In his magical transmission, Cayenne congratulates the team for coming together and expresses his disappointment that Jusis and Laura had chosen to join them. He further tells Jusis that his father was very disappointed when he had heard that Jusis had run away to join his friends. He then impeaches Rean to come and have a discussion with him - hoping to sway the Ashen Chevalier to his side. Rean reluctantly agrees to the meeting and flies up to the Pantagruel in Valimar (after kicking Celine out) in order to protect Ymir and his friends and to find out Cayenne's motives.
On the Pantagruel, Valimar is tied up by Cayenne's subordinates and Rean is escorted at gunpoint to the deck. An the deck, Duke Cayenne addresses Rean and states that he doesn't want the war to continue on as much as he does.He excuses their actions as being a response to Chancellor Giliath Osborne's unreasonable behavior, and he then goes to on list the many atrocities that Osborne had committed e.g. misused the trust that he had with the King, stomped on Erebonian culture and traditions, treated the nation as his own private property etc.
He then asks Rean if he had noticed this and Rean is forced to agree based on his experiences with him. Duke Cayenne then goes and says that now that Osborne is gone, they can now go back and turn back time back to "the good old days." He further suggests that they should now "put aside their differences and join hands." Hearing this, Rean disputes Cayenne's claims with cynicism and labels all of the terrible deeds that the Alliance has done.
In response, Cayenne tries to alter the truth by saying that they have placed the Imperial family under their "protection." Cayenne then continues on with his request that is for Rean and Valimar to join them, so that they can add to their power and publicity of being in the right. He also states that its okay if Rean doesn't agree with their ideals and that the only thing that matters is that they quickly win the war.
Rean objects stating that it's not so simple, but Rufus Albarea and Vita Clotilde both agree with Duke Cayenne and further emphasizes that military might often controls the tide of battle. Duke Cayenne then firmly states his earlier arguments and suggestively implies that if he ever wants his peaceful days back at school with Elise and Alfin Reise Arnor, then he'll have to fight for them - ultimately blackmailing him.
Rufus interrupts again and states that whatever Rean decides, Elise and Alfin's safety is reassured either way. Duke Cayenne agrees to Rufus' proposal. Duke Cayenne then allows Rean time to decide and allows him to walk around the ship freely.
Arrest - S.1206 -
On July 12, S.1206, the Imperial Supreme Court sentences Croire de Cayenne to lifelong imprisonment for, among others, criminal insurrection and treason.