So @warrewell got Vivienne meets a much younger or older version of Lilia, which could not be more fitting considering one of them is immortal and the other is doing naughty time travelling. Basing this that Vivienne perhaps had an incident like the sisters in season 3, and ends up stuck centuries ago and, thankfully and coincidentally, comes across someone who she instantly recognises as a much younger Lilia. It's probably the attitude that gives her away.
Though it had been a few decades since she had left Sicily and Italy, instinct still had Lilia speaking Sicilian or Italian first before remembering that most of the people around her only spoke their native French. She had picked it up quickly, but she didn't like it. Shouting insults in her own native tongue of Sicilian at the woman who had decided she was a 'gitane' and worthy of being spat on, she had turned to find a girl looking at her with what could only be described as dumb shock.
Reading a little of her from afar, Lilia had felt herself drawn closer, her Sight guiding her steps.
"Nun sì di ccà. Parrati puru lu sicilianu? No, non penzu accussì; nun sì di ccà." Large brown eyes took in the girl's appearance. "O talianu? Italiano? No; Inglese. English. And from a different time too, si?" Before the girl could answer, Lilia put a finger to the other's lips, silently hushing her. "No, not here. Cacciatori di streghe. Witch hunters. Come with me."
