Licinia Postuma, more commonly nicknamed Liss, was a legionary who served under Flavius Aetius as part of the Legion of Smoke, a Roman legion whose purpose was to secretly collect items of supernatural and extraterrestrial origin. Kin to the praetorian prefect of Gaul, Licinia's family helped govern the Gallic prefectures and had estates through the country. Her father was a member of the Legion of Smoke and when he died in 445 AD, as his eldest child, Licinia inherited his position within the Legion and learned the true nature of his work. When she joined the Legion her distant cousin, Vitus, was already a member. He helped to train her and the pair were stationed in Gaul together. By that time, stories of mysterious witches called the Tenctrama and their powers were widely known. Licinia and Vitus were tasked with proving that the witches were frauds, a mission made complicated by the fact that the Tenctrama's powers were real.
A female soldier, Licinia's identity was typically obscured by her helmet and armour. Using people's expectations to her advantage, she would plant herself with captives in an adjoining cell and pose as a fellow prisoner to extract information faster.
In 451 AD Licinia and Vitus encountered Graham O'Brien and Ryan Sinclair, lost and separated from the Thirteenth Doctor, in the forests around Catalaunum. Suspicious of the strangers in the midst of the Tenctrama wrought chaos and Hun invaders, they attempted to take the time travellers prisoner. Using smart phone's torchlight to temporarily blind the legionaries, Ryan fled but fell down a hill, and Licinia easily caught up with him on horseback. Ryan then brought up his Spartan warrior avatar in the mobile game World of Combat and bluffed that he could summon the warrior to fight her. Licinia called Ryan on his bluff, but was intrigued by his apparent magick technology and handsome features and did not continue her attempt to capture him. (PROSE: Combat Magicks)