Blythe White

 is Isabelle's thirteen-year-old "sidekick".

Personality
Endlessly cheerful, she never shuts up, causing Isabelle to be annoyed sometimes.

Physical appearance
Blythe has jet black hair with a bright green streak through it and blue eyes.

Phineas Flynn, Ferb Fletcher, and Isabella Garcia-Shapiro
She really is not supposed to be friends with them, being Isabelle's sidekick, but she thinks that they are a lot nicer than Isabelle.

Etymology
Blythe is an English name meaning happy.

Trivia

 * She is also voiced by Alyson Sullivan.

Appearances

 * Isabelle and Blythe