She wants to prove herself. She portrays herself as aggressive to earn respect.
Lil T works with Teresa to prove herself to Big T and the other gangsters. They rob a gang of white supremacist neo-Nazis, and Lil T is especially rough with them, shooting one in the crotch.
El Juicio: Teresa has welcomed into her operation. She is no longer in contact with her uncle. Lil T goes to a church to film Devon's mother singing in the choir, which serves as their leverage -- if they don't let Teresa and James go, Lil T will kill Devon's mother.
El Carro: Lil T is sent with Tonto to send a message to Pecas. Pecas kills Tonto and beats Lil T. She is found with "RETURN TO SENDER" carved into her back.
Diez de Copas: Lil T is given money and sent away by Teresa.
El Carro: Pecas beats Lil T and carves "RETURN TO SENDER" into her back.