Johnny is a teenage boy who is one of Vanessa's friends. Like the rest of the group, he is a goth. Vanessa seems to take a romantic interest in him, as shown in an episode. In Minor Monogram, Vanessa breaks up with him. Plus he is stepson of Vivian Garcia-Shapiro and Vaughn Garcia-Shapiro. He has his appearances from seasons 1 to 3 and the season four episode of Phineas and Ferb Doof 101. Even he’s a friend of Phineas and Ferb just like Vanessa.
His last name is revealed to be "Darc".
In this user's canon, he is the father of a boy named Jonathon.