Author: Kyria d'Oreyn
Marel is the twin sister of Charel, a groom in the Tower stables.
To help a fifteen-year-old Theodrin break her block, Sheriam arranged Marel to take Charel's place - he had to sit in the room during Theodrin's lessons, otherwise she could not have channeled a spark - after a few days. When Marel finally revealed herself to be a girl, Theodrin was so shocked she fainted, but after that she could channel.
(Reference: Lord of Chaos, Chapter 8)