Jonathan Allen is a primary character in the anime series Oh! Family. He is a young American boy, approximately five to six years old, who becomes a central figure in the Anderson household. Physically, Jonathan is depicted as a child with red hair that falls to ear length and black eyes, and he is noted to wear glasses and have freckles. His constant companion is his dog, Adam, with whom he arrives at the Anderson family home.

Jonathan’s background is marked by hardship and instability. Before coming to live with the Andersons, he was staying with a great-uncle in Chicago. He ran away from this situation when his great-uncle threatened to kill his dog, Adam. With no place to go and having run out of money, he resorted to a desperate measure: pretending to be the secret illegitimate child of different men in order to find shelter. This is how he eventually ends up on the doorstep of the Anderson family in Los Angeles, California, claiming to be the son of the father, Wilfred Anderson. His motivation throughout the story is driven by this difficult past; he is a child searching for a place to belong and security after the death of his mother, who was a former girlfriend of Wilfred Anderson.

Jonathan’s role in the story is the catalyst that disrupts and then ultimately strengthens the Anderson family. His sudden arrival and claim to be Wilfred’s illegitimate son creates shock and initial upheaval in their previously orderly lives. His presence forces each family member to confront their own feelings and relationships. A key relationship is with Fee Anderson, one of the daughters, who is initially hostile toward him. This conflict comes to a head when Jonathan, hurt by this hostility, decides to run away from the family. This act prompts a significant change in Fee, who then softens her stance and decides to wholeheartedly accept and adopt him as part of the family. He also has key relationships with his new half-siblings, including Kay, the eldest brother, and Tracy, the younger sister, as well as with Wilfred, who acts as a father figure.

Over the course of the story, Jonathan undergoes notable development. He transitions from a transient child with a fabricated story about his origins to a fully integrated and loved member of the Anderson family. The series, however, features a significant development towards its end. It is ultimately revealed that Jonathan is not, in fact, the biological son of Wilfred Anderson. Upon learning the truth about his real biological father, who is still alive, Jonathan’s journey concludes with him leaving the Anderson family to go and live with his biological parent. Jonathan does not possess any notable superhuman or specialized abilities, his defining traits being his resilience, resourcefulness, and the emotional impact his presence has on the family dynamic.