Phineas Flynn is a young boy in the Flynn-Fletcher family. He is the son of Linda Flynn and stepson of Lawrence Fletcher. He is one of the three children of the Flynn-Fletcher household, with a disapproving older sister Candace and a stepbrother, from Lawrence's side of the family, under the alias of Ferb. He shares a strong bond with the family pet, a platypus they named Perry, but remains unaware of his vague double life as a covert secret agent.
As an incurable optimist, Phineas constantly looks on the brighter side of things. He is also extremely smart, creative, persistent, and able to endeavor in immensely large projects and activities with the help of his stepbrother. His hospitality is a driving force behind many of his plans.