"Calm down, girls. Have you forgotten who we are? We're Fireside Girls Troop 46321 and we never give up!" — Isabella to Fireside Girls troop 46321
Isabella Garcia-Shapiro is the neighbor and best friend of Phineas and Ferb. Isabella has an obvious crush on Phineas. She's the leader of Fireside Girls Troop 46231, and often volunteers to help in Big Ideas, usually with her troop being involved.