Lector is an Exceed, a small, cat-like creature from Extalia, and a member of the Sabertooth guild, one of the most powerful magical guilds in Fiore. As an Exceed, Lector has the appearance of a small, anthropomorphic cat who walks on his hind legs and uses his front paws as hands. His fur is dark brown over most of his body, with pink coloring on his face, belly, paws, and the tip of his long tail. He has large, pointed ears and prominent tufts of dark fur near his cheekbones where his whiskers are located. He wears an open, sleeveless blue vest with three dark round buttons on the right side.

Lector's background is tied to his arrival in Earthland as an egg, a common origin for all Exceeds who were sent from Extalia without knowledge of their homeworld. He first encountered his future partner, Sting Eucliffe, after witnessing Sting fight. Deeply impressed, Lector approached Sting and asked to become his student, expressing a desire to become strong. Sting, though amused by the request, allowed Lector to follow him, and the two formed a close, lifelong bond. During his younger years, Lector would proudly boast to others that Sting had killed a dragon on his own, but when people did not believe him and instead spoke ill of Sting, Lector became deeply upset, prompting Sting to comfort him by promising to one day defeat a mage known as Salamander.

Personality-wise, Lector initially displays a pronounced arrogance. He has a habit of belittling others, believing that everyone is beneath Sting and, by extension, beneath the Sabertooth guild as a whole. During the Grand Magic Games, he constantly expresses certainty that Sabertooth members will easily win every match, and he often scolds his fellow Exceed Frosch for simply asking who might win a contest. When events do not go according to his confident predictions, such as when Yukino Agria loses decisively or when Sting quits a race, Lector is left stunned and speechless. He finds it particularly difficult to process Sting and Rogue's defeat at the hands of Natsu Dragneel, an event that leaves him distraught.

This defeat serves as a turning point in Lector's development. He begins to show signs of humility, telling the guild master Jiemma that Sting learned more from his defeat than from any victory. Lector's core motivation is his deep admiration and loyalty toward Sting. He wants Sting to be recognized as the strongest and is fiercely protective of his partner's reputation. His bond with Sting is the most important relationship in his life. He is also close to Frosch, the Exceed partner of Rogue Cheney, though Lector often grows impatient with Frosch's innocent questions. Within Sabertooth, Lector holds the guild in high regard but is initially indifferent to members who are seen as weak, such as Yukino.

Lector's role in the story is primarily as Sting's companion and emotional support. He is present during the Grand Magic Games as a spectator and cheerleader, and he also serves as a source of information, explaining the concept of Third Generation Dragon Slayers to Natsu and Lucy. A pivotal moment occurs when Sting and Rogue lose their tag battle. That night, the guild master Jiemma violently berates the two Dragon Slayers and moves to expel them. Lector bravely speaks up in their defense, revealing his own Sabertooth guild mark to assert his membership. In response, Jiemma attacks him, seemingly killing him, though Lector is secretly saved by Minerva's magic and kept in another dimension as a bargaining chip. He is later used as ransom, with the condition that Sting must win the Grand Magic Games to see him again. After Sting surrenders the final match, Lector is returned, and the two share a tearful reunion, solidifying Sting's decision to leave behind the guild's former ruthless philosophy. In later arcs, Lector remains at Sting's side, offering encouragement and participating in events such as the defense against the invading dragons and the war against the Alvarez Empire.

In terms of notable abilities, Lector is capable of using Aera, a magic that allows Exceeds to sprout large angelic wings from their backs, granting them the ability to fly. This is a standard ability among Exceeds in Earthland. Lector does not engage in direct combat and primarily uses his flying ability for transportation and support. His greatest strength lies in his emotional connection to Sting, serving as a motivation for Sting's growth as a leader and a person.