Lavinia

Lavinia is the acting guildmaster and Grand Arbiter Pro Tem of the Azorius Senate on Ravnica. Formerly, she was an arrester in the Tenth District and the Steward of the Living Guildpact Jace Beleren. She is straightforward, stern, and seldom smiles.

History
Lavinia's brother was a member of the Azorius, having trained at one of their academies. Unfortunately, soon after he graduated, he ran afoul of the Dimir and Rakdos. The groups tracked down the pair, and her brother ultimately paid for his sister's safety with his life. Lavinia killed the torturers herself, but not in time to save her brother's life. The next day, she left the Ninth District behind her and took her first steps to become an arrester.

Arrester
Lavinia became embroiled in the conflict surrounding the Implicit Maze when a building owned by Jace Beleren burnt to the ground. When she arrived to investigate, she found a conspiracy surrounding the telepath and demanded he come in for questioning. The mind-mage resisted and then fled to his destroyed domicile where his accomplice, an ogre by the name of Ruric Thar, helped him escape. During the ensuing conflict, Ruric Thar shrugged off the magic and wounded several of the arresters assigned to Lavinia.

She made her report regarding the arson and conspiracy but was told, in no uncertain terms that she no longer had any interest in the case. When she disagreed and requested to continue her pursuit of Jace, she was reassigned and confined in the towers of New Prahv with the clear understanding that this "promotion" was to keep her out of the matter. She very nearly betrayed every value she held dear, abandoning her post, but ultimately she could not bring herself to do it. There were still other avenues that she could exploit without disobeying her orders.

To her surprise, her research would pay off far more than she could have expected. As she gathered materials relating to the maze uncovered by the Izzet, the one that Jace himself had been researching, she found the fugitive coming to her for further information. She gave him very little about what she had learned but was all too happy to pressure Jace to turn himself in. The mind mage refused and left none the wiser, having tipped his hand to the arrester.

Mazerunner
Lavinia once again appealed to Isperia after Niv-Mizzet announced the participation of each guild in the maze. For her troubles and obvious insider knowledge, Lavinia was chosen to run the maze representing the Azorius. She had also learned that the ultimate goal of the maze was to be the Supreme Verdict of Azor, and was left with questions of why the parun would choose to build the maze.

Once the event began, Lavinia took the opportunity to, at last, arrest Jace as he accompanied Emmara Tandris through the Azorius Guildgate. Jace willingly gave in to stand trial with Isperia herself. He was found guilty of his crimes to Lavinia's immense satisfaction, but his punishment was to be community service: To see each maze runner complete the maze. Lavinia was stunned but had little choice but to honor the guildmaster's wishes.

Once the maze was completed, she once again sought out Jace, now in his new offices. He planned to form a council to govern the guildpact, and asked Lavinia to be a part of it. Reluctantly, or more appropriately, suspiciously, she agreed, if only to keep an eye on Jace. She became Jace's aide and deputy at the Chamber of the Guildpact.

Deputy of the Living Guildpact
Lavinia managed affairs while Jace was away on Zendikar and Innistrad, dealing with the Eldrazi threat. Afterward, she was informed about his planeswalker nature and his affiliation with the newly formed Gatewatch. After some ratifications from Jace, she was willing to allow them in his residence. When Dovin Baan arrived from Kaladesh to hire the Gatewatch as a security force, Lavinia also brought news of a series of petrifications of several influential Azorius members. This led Jace to suspect that Vraska could have returned. Lavinia was tasked to cooperate with Gideon Jura to learn more about the assassinations. When Chandra disappeared along with Liliana, Lavinia forbade Jace to leave Ravnica again for such a long time, reminding him of his duties as the Living Guildpact. Jace left anyway when Liliana Vess reported that she had seen Tezzeret on Kaladesh.

Rebel
Jace's disappearance worried her, but she steadfastly refused to violate the law of the land by stepping into his duties. However, she also refused to acknowledge Dovin Baan's authority when he became guildmaster after Isperia's assassination by Vraska and was leading a rebel faction within the Azorius to overthrow him. She warned Ral Zarek against the agents of Bolas, that had infiltrated the guilds. When he thanked her, she stated that she was still doing her job: defending the Guildpact and Ravnica. She was on the trail of Bolas' main agent, who turned out to be the planeswalker Tezzeret. As she found him, she walked into a trap. Tezzeret outmatched her and placed a device on her neck, that turned her into an unwilling accomplice of Bolas.

As Ral Zarek, Kaya and the Rakdos emissary Hekara banded together to activate the Interplanar Beacon to get help against Bolas, they were opposed by Vraska and the possessed Lavinia. This led to Hekara being killed by Lavinia before Ral Zarek could free her from Tezzeret's device and she gained control of her own body again.

War of the Spark
During the War of the Spark Lavinia was tasked with Chandra, Nissa, and Saheeli (plus Lazav) to shut off the Immortal Sun. They managed to do so after defeating Dovin Baan, and many planeswalkers left right then. She served as the representative for the Azorius Senate, at the resurrection of Niv-Mizzet as the new Living Guildpact.

Aftermath of the War
She survived the War and became acting guildmaster of the Azorius. She refused to become Deputy of the Living Guildpact again. As Grand Arbiter Pro Tem she strove to reform the Azorius after the twin plagues of Bolas and Baan, while simultaneously seeking her own replacement. Seeing the irony of having to carry the responsibilities, Jace Beleren wondered if she just wouldn't be the perfect choice to continue as guildmaster.

Trivia

 * Lavinia was originally quoted as Arrester Lavinia, Tenth Precinct. However, there are only six precincts in the Tenth District. Lavinia of the Tenth seems, therefore, to refer to the Tenth District itself.