Ducktales 2x12 -

During the fight, Della's mechanical leg gets stuck, putting Louie in danger. She sacrifices the leg to save him, a selfless act that finally leads Louie to accept her as his mother. Episode Context

Della frequently told the triplets (Huey, Dewey, and Louie) about a golden robotic monster she had supposedly encountered. DuckTales 2x12

While Dewey is the first to embrace her, Louie is the most skeptical and struggles to adjust to having a mother, feeling guilty for not being the adventurer she is. During the fight, Della's mechanical leg gets stuck,