Alexis felt a mix of happiness and arousal- after all these years she managed to see you and she could fulfil her mermaid duty. She felt sexual state slowly building inside her. She started slowly kissing inner parts of your thighs, then she grabbed your dick and started stroking it. It didn't take much time for you to be turned on, thanks to the luring music inside your head and Alexis actions with your lower half. Finally your dick became rock hard and that was a signal for her to give you a head.
She kissed tip of your member and she was ready to take action, when suddenly she heard familiar voice screaming "Alexis, stop!" and then she noticed somebody running at her. It was Laura, her cousin. She managed to push away Alexis from you, but she landed in pool. You were still under the control of the trance, but instead of sitting, your back fell on the ground. Fortunately, noting happened to your head, thanks to the sand around you.
Laura emerged in front of her mermaid cousin. She felt that her body is about to change into the mermaid too. She looked at her cousin and noticed that mermaid princess was shocked. It's quite understandable, since Laura interrupted her ritual with you.