"Relax, I would have to mark you as my own anyway and I see no reason to cause you more pain than is completely necessary" Lucius told her as he looked back over his shoulder at her.
Although the ritual would most certainly not be pleasant for Evie, by doing it in this way he would have more than enough power to ensure a clean and swift healing once he was done. It would only hurt for as long as it took him to complete his symbol.