Emily meets Aaron in the third book of the series when she finds the Castle in the Mist. As she is leaning against a door, it suddenly opens, for her to see his "piercing green eyes". Aaron is a tall skinny boy who is wearing black flared pants and a black T-shirt when Emily first meets him. He has long, black hair parted perfectly in the middle, and thick black eyelashes. Aaron has a pale face that is serious, as is his voice, which is also silky smooth.He has lived in Half Light Castle all his life and has never left. His mom is alive and his dad is dead. He is a decedent of Neptune and his family always dies young. It is apart of their curse. All the men in their family mostly die from them trying to figure out the curse. Almost semi-mer, Aaron's hands and feet are webbed, and when he sees Emily's tail melt away into her legs, he says he can't do that. His legs stick together and his toes flap, but that's about all. Emily has to break the curse for herself and Aaron.

When Aaron is able to fully turn into a merman, he has a black tail.

Aaron and Emily grow fond of each other, starting in Siren's secret. At the end of the book they have their first kiss. They become boyfriend and girlfriends in the 5th book. Aaron and Emily both get tingly feelings from their fingers to their arms whenever their hands touch because when they first kiss they got their power back.In the 5th book they have their first argument and break up. At the end of the book they get back together. Aaron admits he loves Emily Windsnap in the 6th book, and Emily also admits she loves him.