Alex shares the typical Harman appearance; the baby has silvery blond hair and violet eyes, just like his sister. Being a toddler he is small, but has a very strong grip, causing the shapeshifter Keller to mentally quip that the family may have sloth shapeshifter blood among the gene pool.
Despite his young age, Alex has displayed several supernatural abilities even before Iliana, including precognition (sensing the future); he is a lost Harman like his mother and sister. He is also able to detect that Keller is a panther shapeshifter, affectionately calling her "Kee Kee" (Kitty), and shows joy being around and talking to her.
Alex is introduced when Keller and her team first arrive at Iliana's home in North Carolina; he is sitting at breakfast along with the team and his family, eating Cheerios. He eventually manages to get out of his high chair and toddle over to Keller, calling her "Kee Kee" and holding out his arms to be picked up. Although Keller is successful at getting him off her at first, Alex returns to her, climbs into her lap and hugs her, kissing her cheek and giggling; Iliana mentions that they "look sweet together". Alex calls her "Pwee!" (Pretty), and Iliana's mother notes how well he takes to Keller, as Alex normally prefers animals. With some effort, Keller is able to get him off and awkwardly gives him over to Mrs. Dominick, dismissing the baby's assessment of her as pretty (although the shapshifter prince Galen agrees with Alex).
Alex goes to the door as Iliana departs for the Ashton-Hughes party, Keller and her team escorting the girl. Keller is disturbed when Alex's face "crumpled" after she had blown him a kiss at Iliana's insistence. Alex begins crying and calls out goodbye repeatedly to Keller, leading the witch Winnie to think Alex might possibly be able to see the future. Although not stated, there is an implication that Keller thinks Alex's farewell is a warning she might die that night.
During the party, Keller becomes alarmed, suspecting the Night World might have threatened or even taken Alex. After surviving the dragon's attack and making it to the Solstice celebration, Keller calls Mrs. Dominick; Alex, perfectly fine, interrupts the phone call with a happy "Kee Kee!" Keller gladly quips about how Alex has much "to learn about precognition", even revealing she had at one point thought he might be the Wild Power, but confirms Alex's status as "just a good old-fashioned witch baby". Iliana, passing at the time, is incredulous over the fact that Keller is having a conversation with her brother.