Alyssa Thomas is Rachel Thomas's sister and close friend of Emily Kinney and Marie Munro. She normally is a leader, and is very senstive and gets angry if you hurt or tease people. She stood up for Phineas and defended him in one episode when a group of bullies threatened to beat him up. She makes good friends with Phineas, Ferb, and Isabella. She gets along well with all of them and knows of Emily's crush on Ferb. She is very sweet, kind and loving. She can get quite annoyed with Phineas if Isabella is really obvious that she likes him and he does not notice.