Rewatching season 4 I had this insight about when C realized that she has feelings about Q. The timing of her father's death is perfect. She lost so many people, she is worried about Q and then suddenly her father just die. when she was talking to her sister she reacted all "wow" and a little weird. She was actually thinking about Q and how she really can't lose him not only because she cares but because she loves him. And this just gives her even more strength to go after him and save his life.
Actually, this is a really good point, Anon, and one that we often overlook. I absolutely agree that her father’s death was an eye-opener for Carrie ITO how she felt about Quinn. She was already set on finding him, but after the news about her father, her mission took on a whole new level of desperation. The prospect of losing Quinn on the heels of her father’s death was too much for her to bear 😢. An absolutely pivotal moment for Quarrie.