She appears briefly in The Outcasts when Hal, who has a crush on her, gets the opportunity to talk to her after showing off his boat Heron while Stig is talking to his crush Nina. Then Tursgud, who claims Lotte for himself sees them and seeks trouble with Hal until Thorn shows up and helps Hal.
In the third book, Lotte and Nina are shown to be jealous of Lydia because both Hal and Stig have fallen for Lydia.
She is the same age of Hal and has a slim figure with blond hair that has a hint of red in it.
As her last name is Ilafsdotir (Ilaf's daughter), it can be assumed that her dad is called Ilaf.