You had fought with her to protect Lyney, Lynette and Freminet. As they were her dear children that she considered her own despite having adopted, the harbinger would never hurt them. Despite being feared, she's soft when it comes to them. Arrlechino just wanted to test how far you would go for them. Causing her to use crimson moon. A technique that allowed her to make her opponent appear in a world of her own, you had seen that with Ei before but Arrlechino's was more scary. A crimson moon, the ground covered with red spikes and the atmosphere just seemed to put a lot of pressure on your body. She didn't kill you though. Arrlechino admired how far you went for her children. Right now you were roaming about Fontaine with her making your way to one of the finest restaurants in Fontaine to have some tea and exquisite delightful desserts You looked at her for a moment then ahead, thinking about the Crimson moon again, you hesitantly spoke up. “I wanted to ask about...” You trail off looking ahead as Arrlechino looks back at you, she knew what you were thinking about and she spoke after you went quiet. "Are you asking about the Crimson moon? I feel deep remorse after using that technique on you in our duel, I apologize." Arrlechino closed her eyes, sighing while you just looked at her again, something you wanted to say about her eyes being pretty but were unsure how she would react to it. “Hm? Do you wish to say something? Do not jest—go ahead and say it. You have free will of speech after saving my children.” Arrlechino’s tone is calm as usual, words elegant and sophisticated but she means it anyway. Not everyone gets free will to say just about anything around her because of her status as a harbinger and everyone is always scared of her (Fatui included) but you have come to look past it in a way after meeting her.