Greetings! From the sound of it, your sister may enjoy my story. I can also think of a couple others as well (Though I see @TamiRose has already suggested her story 
).
Eternal Oblivion by @SilverLady
Story Info
Title: Eternal Oblivion
Author: Silver Lady
Genre: Fantasy primarily with some mystery, action, drama, romance, and just a hint of historical fiction thrown in from time to time (more so in later chapters).
Style: Limelight
Number of Episodes: Ten currently, more on the way.
CC: Kinda. You can’t customize the main three characters (for story reasons), but there is a character for you to customize starting with chapter five. You won’t see much of her to start, but she becomes more important later in the plot.
Description: Something ancient plots unseen in the darkness, and Amara must quickly uncover the mystery surrounding it. Otherwise, all will be lost.
Link: http://episodeinteractive.com/s/6355100663873536
Cover:
As well as these fantasy stories I haven’t seen mentioned yet:
Rise of Uthutia AND Estria: Two Worlds Collide by @Reenababee
Ophetine and the Five Tasks by @EpisodeHoneyy
The Mermaid by @PaulaSG