Benedict Blue works as a postman for the CH Postal Company. Originally not from Leiden, he traveled with gypsies in his youth, learning their songs and dances. His past includes serving as a mercenary and gladiator on another continent, where he was ultimately abandoned in the desert. Claudia Hodgins rescued him there, bestowed the name "Benedict Blue," and formed a long-standing association with him prior to establishing the company. Benedict was instrumental in founding the CH Postal Company from its very beginning.

He presents as a slim young man with strikingly bright sky-blue eyes, light skin, and short, spiked sandy-blond hair featuring a longer forelock framing the left side of his face. His distinctive attire typically consists of a loose spring-green shirt (beige in the anime), pale-golden suspenders, military-green tight leather pants, a black or grey undershirt, and fingerless gloves. His most recognizable feature is his long black boots equipped with tall cross-shaped heels, which frequently cause him to sprain his ankles due to balance difficulties.

Benedict exhibits a brusque and short-tempered personality, often speaking bluntly or rudely, particularly to Hodgins. He is straightforward, insensitive to social nuances, and vocal about his thoughts, sometimes offending others. Despite this exterior, he possesses a kind and considerate nature, especially towards those he cares about. He is diligent in his work and shows leadership among the postmen. He displays chivalry, such as insisting on accompanying Violet Evergarden during demanding tasks, motivated partly to avoid Hodgins' reprimands but also out of genuine concern. An innocent side emerges in interactions, like blushing in intimate situations or reacting strongly to rejection, such as when receptionists declined his lunch invitation.

His relationships are multifaceted. He shares a deep, longstanding friendship with Claudia Hodgins dating back to before the company's founding. Despite Hodgins being his employer, Benedict maintains an informal and often intentionally annoying demeanor, though Hodgins mentors him in social graces. Benedict has a contentious rivalry with Cattleya Baudelaire, frequently exchanging insults and arguments; however, they cooperate when necessary, like when she treated his injured ankle. While mutual dislike is evident, some sources suggest an underlying romantic connection. Benedict develops a significant bond with Violet Evergarden. Initially unnerved by her, he becomes protective and brotherly, mentoring her in postal duties and offering emotional support. He nicknames her "Vi" and assists in her personal challenges, such as finding a guardian for Taylor Bartlett. A short story depicts their evolving closeness, including attending a wedding together and searching for a gift for Hodgins. Benedict confides in Violet about his amnesia and search for a long-lost sister, fueling recurring speculation about a potential sibling relationship between them, reinforced by their similar appearances and shared history tied to the Great War.

His skills reflect his mercenary past, encompassing combat proficiency, speed, and firearms expertise. He delivers mail efficiently and handles dangerous situations adeptly. For transportation, he initially used a worn blue bicycle, later receiving a golden motorcycle from Hodgins as a reward.