Isi Dawndancer debuted in the book series in the Monster High Diaries series in "Frankie Stein and the New Ghoul at School" in the Monster High franchise in early-to-mid July or May in 2016. She certainly has appeared later now.
Isi is paired with Venus McFlytrap to help Frankie get her pettish little sister (sister by creation in a lab) Zappit back. After Isi goes home, Frankie Stein suggests to her parents about creating a pet to keep Isi company. Later, Isi meets Frankie, who tells her that Zappit returned to her den in the woods. Frankie asks her if she would like to take care of Zappit, which Isi says yes. Isi is so happy that she invites Frankie to a bonfire party to say thank you. Frankie joins her friends at the bonfire, where Isi thanks her for being such a good friend, and reminds her that even though she doesn't have a big family, her friends are very much her own pack.