Isabella is very beautiful, cute, adorable, sweet, caring, slightly sarcastic, determined and also very helpful, always spending her time getting the Fireside Girls to help Phineas and Ferb with their projects.
Isabella is sympathetic and aids people who are in need of help. This has been demonstrated when she showed concern for Candace, who was too nervous to call Jeremy and ask him out, when she snapped Phineas and Ferb out of their hypnotic dullness, and when she stopped telling Phineas her feelings about him to help Ms. Feyersied.
Being a Fireside Girls Troop Leader, Isabella is a very capable leader. She is level-headed and responsible in the face of emergencies and dislikes being told what to do by anyone, with the exception of Phineas.
As nice as Isabella would seem, she can get angry. One way her temper has been flared is when someone else uses her catchphrase; in such a scenario, she expresses annoyance and often confronts the violator physically. However, she is fine whenever Phineas uses it.
Another is when she isn't a subject of attention. Isabella enjoys attention, she openly displays discontent when she feels she isn't receiving enough of it. She has shown this when Phineas expressed seeing Meap as cute but not her, and when her Li'l Sparks men-tee, Melissa, showed Candace more attention and admiration than she did with her.
Isabella wears a sleeveless knee-length pink dress with a dark pink or fucshia belt, a white t-shirt and a bright pink bow on her head (her default outfit is similar to that of Helga G. Pataki). She also has long elbow-length black hair and dark blue eyes.
Though the articles of this page involves Isabella, Phineas & Ferb series also introduced other incarnations of the characters, be it Isabella's own lookalike, ancestors, and alternate interdimensional counterparts. Following alternate Isabellas introduced in the series are:
2nd Dimension Isabella
This Isabella is a battle-hardened soldier who have involved in the constant war against the more ruthless 2nd Dimension Doofenschmirtz until our world's Phineas and Ferb's involvement where they finally put the end of the war and freed Tri-State Area from the dictator. While in terms of personality, this Isabella is tough, no-nonsense, and down to earth as result of Pinky's disappearances and the war, but this form of personality only displayed in the battlefield, as in her normal life, she's not so different with our dimension's Isabella.
- Isabella is very similar to Colin (The Simpsons Movie).