Fandom: Marvel - Thor
Lya is Thor's younger sister - the goddess of Deception. She takes after Loki and her mother, using magic and spells. She can take the form of anyone if she has an item of theirs.
When Loki is imprisoned for attacking Midgard, she's the only one who visits him in his cell. She relates to him more than Thor.
She helps Thor free Loki and goes with them to the Dark World.
When they're attacked by dark elves, she stops Loki from helping Thor, steals one of his daggers to take his form, and attacks Kurse. She dies in Loki's place, making Thor believe his brother is gone.
Loki finds her after Thor and Jane are gone. He returns her body to Asgard in the form of a palace guard and takes the throne.
Thor returns and discovers that Loki has been posing as their father, and so, finds out about Lya's death.
That was short, but she doesn't really do much. She's pretty much just there for Dark World. I use her as an explanation for how Loki survived getting stabbed through the chest. 😅