Accaiou

Epistolary Accaiou is a young but powerful Librarian of the fierce and savage Storm Angels Space Marine Chpater. Despite his relative youth, he has already proven himself to be a level-headed and talented practitioner of the psychic arts. He possesses a burning hatred for all things Chaos-related, and endlessly seeks out hidden heretic cults and individuals who make truck with the Ruinous Powers. During the events of the Long Dark, it fell to the young Epistolary to seek out the forces of the Indomitus Crusade, and later, play an instrumental role in helping his Chapter to decide to become Rubicon Primaris as an alternative to not accepting the newly revealed Primaris Space Marines into their ranks.

Background
Young but calm-headed, Accaiou has demonstrated his talents both as a psyker and a preserver of knowledge and lore. While his youth was unremarkable, he succeeded in being selected as an Aspirant for the Storm Angels and underwent the transformation from a savage kid to a newly formed Astartes. however, the changes in his body unlocked latent psychic powers and he had to face the unwanted attentions of daemons, which tried to possess his body to wreak havoc on the Storm Angels.

Only thanks to the Librarians purging the repulsive slaves of the Dark Gods did Accaiou preserved his own self being. From this ordeal, he was granted with a burning hatred of all things Chaotic, making it his life-work to hunt and purge any and all chaotic corruption on the worlds the Chapter operates. During the Long Dark, he requested and was granted multiple squads to track down and destroy minor demons and heretic cults trying to summon the greater abominations from the Warp.

When three Companies were dispatched to the Indomitus Crusade, Accaiou was tasked with counseling and supporting the Second Captain Akodu, a task he disliked, for the two men are like water and oil. However, he accepted, for to pass on the opportunity to see a living Primarch and bring this knowledge back to his Chapter was an unacceptable idea for him. He was the one who, through some tense discussions, managed to convince Akodu to request the knowledge of the Rubicon Primaris over refusing outright to add Primaris to the Storm Angels' ranks.