Diego Flynn

Physical Appearance
Diego seems to have inherited more physical attributes from the dad, as he has a triangular head, black hair, a blue-and-red striped shirt,  green cargo shorts, and red sneakers.

Personality
Willow calls him an annoying little twerp. He annoys her to no end, especially when he wakes her up for no apparent reason. Willow can sometimes be seen chasing him around the house, normally because he has something of hers, most likely her diary.

Phineas Flynn
Diego loves and respects him.

Isabella Flynn
See Phineas.

Willow Flynn
He is always looking for ways to annoy his sister.

Haily Smith
They often are together. Willow calls her his girlfriend, much to his annoyance.

KC Greene
They have a normal friendship.

Xavier Brown
See KC.