A native of Brittany in what is now northwestern France, Nolwenn made a name for herself as a smuggler in the city of Paris in West Francia, smuggling goods and messages in and out of the city. It was such that by the 880s, she had familiarized herself with the city's layout and know its every entry and weakness. Sometime prior to 886, Nolwenn had a brief romantic relationship with Toka Sinricsdottir, a Viking from Elgring Clan based in Melunois. The relationship ended once Nolwenn left Toka abruptly and stole her necklace in the process.
Nolwenn was also a close friend of Queen Richardis, the wife of King Charles the Fat. After the Viking attacks around Paris and region left many parts of the city in despair and plague ridden, Richardis sought Nolwenn's aid to provide medicine and food to the local population. They would use a warehouse near Saint-Julien as a way to rendezvous without being discovered.
Because of her familiarity with the city layout, Nolwenn was sought out by the Viking Eivor Varinsdottir of the Raven Clan, who had been sent by Toka to seek her out for a possible weakness in the city walls. Eivor managed to track down Nolwenn with help from Richardis and Bernard, eventually finding her in the tunnels struggling against several bandits. After the bandits were killed, Nolwenn thanked Eivor for her assistance and learned that Eivor had sought her for help in preparation for their siege. After some reluctance, Nolwenn eventually provided Eivor the information of weakened bridges connected to the city, suggesting by the destroying them would allow the Viking longships to encircle the city easily. With her aid given, Nolwenn left the tunnels.
Nolwenn became present during the siege as she called out to Eivor. From their interaction, Nolwenn led Eivor down through the tunnels, going to the Palais de la Cité. After their arrival, Nolwenn left Eivor and wished her luck on her mission.