Adam is a significant character in the anime Oh! Family, known primarily as the beloved pet and inseparable companion of the boy Jonathan. He is a large, hairy dog whose physical presence is considerable enough that a child can comfortably ride on his back, a feat demonstrated in the first episode when a character named Tracy does so. Adam shares an exceptionally deep bond with Jonathan, having been with him since the moment of his birth, making them not just master and pet, but two friends who have grown up together and share a profound connection.

In terms of personality, Adam has a notable and somewhat comical trait of frequently falling in love with human women, showing a distinct preference for them over other dogs. This tendency is highlighted by a genuine infatuation he once had for a character named Laura, showcasing an almost human-like romantic inclination. Another defining characteristic is his hearty appetite; Adam is described as being somewhat overweight due to his love of eating. This is humorously emphasized by a doctor's remark that, given his size, he could survive for a month without food or water.

Adam's role in the story is intrinsically tied to Jonathan's sudden arrival at the Anderson family home in Los Angeles, California. When Jonathan appears claiming to be the father's illegitimate child, Adam arrives with him, immediately becoming part of the ensuing family chaos and eventual acceptance. His primary relationship is, without question, with Jonathan, as the two are presented as a united pair. Through his master, Adam becomes a member of the Anderson household, interacting with its various members, including the initially hostile Fee, the mother Sharen, and the father Wilfred. His presence often adds a layer of warmth and gentle humor to the family's daily adventures and emotional upheavals.

While Adam does not undergo a significant personal transformation over the course of the series, his development is reflected in his unwavering loyalty and the consistency of his nature. He remains a stable and loving presence for Jonathan, who himself faces the uncertainty of not truly being a member of the Anderson family. Adam's primary ability, beyond his physical strength as a large dog, lies in the emotional support and companionship he provides. His size allows him to serve as a form of transport or a living playground for the children, but his most notable ability is his deep, intuitive bond with his master, which serves as an anchor for Jonathan throughout the family's trials.