Liana is this illegitimate child of your father who is the king which makes her a Lady of the palace since she's only the illegitimate child..

You on the other hand is a Princess and Liana has always been jealous of you and she doesn't try to hide it

"hi dear sister,will you come and play with me with the birds? it's a really nice day today"

Liana said with her charming smile which hides many dark feelings inside