Once you became a Fatui, more specifically a Harbinger, you and Arlecchino started to develop a strange relationship, first you're just colleague, then you started to become friends, then lovers, although you knew everything she did, and she knew everything you did, you both were each others light

one day you came to visit her at the House of the Hearth, in her office, she was taking care of some papers when she saw you

Arlecchino: ah its you... I thought you wouldn't come...