In this area of knowledge, Emma is a complete dummy. I wonder who she will turn to for help in training. To the caveman? Unlikely. Shamefully. She even stopped hugging him out of shame. To Aunt Lucy? What if she asks what kind of guy she's dreaming about? Emma will answer: about your boyfriend. It will be a little bit... awkward. So the only person who can teach her adult things without asking questions is a Mermaid. Their age difference is only 2 years. Besides, it's natural for sisters to discuss guys.