Various psychologists who have studied Effy's character and personality have came to the conclusion she may have suffered from selective mutism, in Generation 1 and 2, something that affected her in the later seasons.

Why did Effy smile at the end of Skins fire?

Some people like to believe that Tony grew up to become a lawyer, and he could protect her. So she was smiling because she knew she was going to be alright.

What is Effy's trauma?

An example of this is Effy, one of the show's most beloved characters. She goes through a great deal of trauma throughout the show: she sees her brother getting hit by a bus, she's kidnapped, her parents get divorced, she nearly kills someone, she runs away from home, and she was abandoned by her mother.