Rob and his wife also share a strong love for the sea and used take many walks on the beach together when they were a younger couple. They tried for many years to have a baby, but were unsuccessful and would wish for a child of their own. Unknown to them, their wish had been heard by a mermaid named Nerissa, who was unable to keep her infant son due to the Northern pod from which she came being under siege by a corrupt mermaid named Aurora. Wanting him to be safe and happy, Nerissa leaves her son on the beach for Lauren and Rob to find. While out on their usual walk on the beach, they suddenly hear a baby crying and go to investigate. They are overjoyed when they discover a baby boy. Although they try to find his birth parents, no one claims him and so Lauren and Rob eagerly legally adopt him as their own son and name him Zac.
As Zac grows over the years, he comes to share his parents love for the sea. Rob and Zac also start a yearly tradition of a father and son camping trip. However, Lauren and Rob do not tell him about how they found him, and Zac grows up always believing that they were his true biological parents. This would later come back to haunt them when Zac learns of his true identity as the son of Nerissa and brother of Mimmi. Greatly stressed by this revelation, Zac talks to his parents who are then forced to tearfully admit the truth. Later, they tell him the story of how they found him and explain that the reason they never told him until now is because they always considered him their real son. Rob then shares a loving embrace with his family as Zac then makes peace with who he is and realizes he was truly meant to be with him and Lauren.
When Zac later reunites with his biological mother Nerissa, Zac decides that the time has come to tell Rob and Lauren who he really is. With the two of them haven taken Zac in and giving him love and care while Nerissa was unable, Zac concludes that they deserve to know the truth.
- Before Season 2 launched he was introduced as Zac's biological father.
- At the end of season three Zac said that he would tell his parents about his real mother. He will eventually know that his adoptive son is a merman and about their world.