Jon Ace is portrayed as a former member of the organization S.T.O.R.M. who eventually becomes a significant ally to the protagonist Chase Suno and his team, Core-Tech. Initially, Ace served as a S.T.O.R.M. liaison and the helper and guardian to Jeredy Suno, Chase's father. Through countless hours of shared research, Ace developed a deep-seated respect and admiration for Jeredy, establishing a strong and trusting relationship with him.

Personality-wise, Jon Ace is depicted as a character torn between the strict, often severe methods of S.T.O.R.M. and his own strong moral compass. This internal conflict defines much of his early behavior, as he struggles to resist his natural instincts to shield and guide the younger Chase from the organization he works for. He is dedicated to protecting the innocent, but his affiliation with S.T.O.R.M. frequently puts him at odds with his personal beliefs.

Ace's primary motivation stems from his loyalty to Jeredy Suno and his desire to protect Jeredy's son, Chase. He eventually resigns from S.T.O.R.M. with the explicit intention of guarding Chase from the dangerous situations that lie ahead. His role in the story evolves from an adversary who reluctantly battles Chase to a crucial guide and protector. After resigning, he leads Team Core-Tech through various perils, such as the Bangli Jungle, while they search for Jeredy. At one point, he even attempts to destroy a chunk of raw Monsuno Essence, believing it to be far too dangerous.

Key relationships in Ace's life center on the Suno family. His bond with Jeredy is built on mutual respect and shared research, while his dynamic with Chase is more complex, shifting from a guardian assigned by S.T.O.R.M. to a self-appointed protector and trusted ally. Following his resignation and throughout his journey with Team Core-Tech, he builds a working relationship with the young members of the group.

Jon Ace undergoes a significant and dramatic development when he is mutated into a semi-Monsuno hybrid form known as Toxic Ace. This occurs following an explosion of Monsuno Essence at a mining facility. In this monstrous form, he is captured by the villainous Dr. Emmanuel Klipse and forced to fight against his former allies. While under Klipse's control, Toxic Ace proves to be a formidable threat, easily defeating multiple Monsuno at once. His development reaches a turning point when Jeredy Suno successfully reaches the humanity within him, reasoning with him about the actions the real Jon would take. Toxic Ace then breaks free from Klipse's control and guides Jeredy to safety. Ace eventually returns to S.T.O.R.M. as the new Commandant Marshall after helping to save the world.

In terms of notable abilities, as a human, Jon Ace is a capable Monsuno controller. His primary Monsuno is Blackbullet, which he reluctantly uses against Chase in an early battle, and he later comes to possess Goldhorn. After his transformation into Toxic Ace, he gains new abilities inherent to his Monsuno-like form, including enhanced strength and the power to quickly rejuvenate from damage. He also demonstrates the ability to control his Monsuno transformation at will.